首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4559篇
  免费   283篇
  国内免费   1篇
各国政治   351篇
工人农民   15篇
世界政治   765篇
外交国际关系   766篇
法律   1542篇
中国共产党   307篇
中国政治   569篇
政治理论   176篇
综合类   352篇
  2023年   29篇
  2022年   30篇
  2021年   33篇
  2020年   31篇
  2019年   40篇
  2018年   52篇
  2016年   34篇
  2015年   35篇
  2014年   160篇
  2013年   112篇
  2012年   259篇
  2011年   285篇
  2010年   182篇
  2009年   151篇
  2008年   208篇
  2007年   200篇
  2006年   238篇
  2005年   193篇
  2004年   177篇
  2003年   187篇
  2002年   189篇
  2001年   136篇
  2000年   109篇
  1999年   79篇
  1998年   71篇
  1997年   76篇
  1996年   69篇
  1995年   95篇
  1994年   97篇
  1993年   71篇
  1992年   62篇
  1991年   56篇
  1990年   56篇
  1989年   64篇
  1988年   95篇
  1987年   80篇
  1986年   82篇
  1985年   90篇
  1984年   88篇
  1983年   88篇
  1982年   58篇
  1981年   61篇
  1980年   76篇
  1979年   35篇
  1973年   14篇
  1964年   21篇
  1962年   16篇
  1959年   16篇
  1957年   16篇
  1956年   13篇
排序方式: 共有4843条查询结果,搜索用时 0 毫秒
171.
172.
The ability of 1,2-indanedione and 5,6-dimethoxy-1,2-indanedione to detect latent prints on porous surfaces, as compared to DFO and ninhydrin, has been evaluated. Comparisons of prints developed under various conditions determined the optimum development conditions for the new reagents. The indanediones tested were found to have lower detection limits for glycine. The carrier solvent used was found to affect the quality of the prints developed. In Arklone, the new reagents developed prints that displayed superior luminescence to those developed with DFO. In HFE 7100, 1,2-indanedione and 5,6-dimethoxy-1,2-indanedione gave superior luminescence to DFO after zinc salt treatment and cooling with liquid nitrogen, both of which improve the luminescence of prints developed with 1,2-indanediones. 1,2-Indanediones could offer less expensive but effective alternatives to DFO. With further optimization, the new reagents may supersede DFO as the method of choice for the detection of latent fingerprints on porous surfaces.  相似文献   
173.
A blood group substance (BGS), a protein with ABH antigenic activity, was isolated from human seminal plasma and designated as p 84 (Sato, 1995). We have developed a method for determining the ABO blood type of semen by performing a sandwich enzyme-linked immunosorbent assay (ELISA) in which p 84 is captured with an anti-p 84 monoclonal antibody, and evaluated the specificity and sensitivity of this method. Although BGS activity was detected in semen sensitively by this method, it was not detected in saliva, urine, breast milk, blood or vaginal secretions. Since the concentration of p 84 in semen was independent of the secretion status, the status can be determined as non-secretor when p 84 but not BGS activity was detected. To determine the stability of BGS activity on p 84, dried stains of semen on filter paper were kept at 4, 26, and 37 degrees C for 8 months, 2 years and 1 month, respectively, and their BGS activities were examined. After 8 months at 4 degrees C, over 60% of the original BGS activity was recovered from the stain. The activity could be detected even from a square as small as 0.25 by 0.25 cm. After 1 month at 37 degrees C and 2 years at 26 degrees C, 31 and 20% of the BGS activity, respectively, still remained. It could be detected from the pieces of 1.0 by 1.0 cm and 0.5 by 0.5 cm squares, kept for 1 month at 37 degrees C and 2 years at 26 degrees C, respectively. Finally, semen was mixed with saliva or blood at varying volumetric ratios and used for the sources of dried stains. The BGS activity of p 84 could be detected in the stains until the ratio between semen and saliva or blood reached 1:4. We conclude that this sandwich ELISA offers a more sensitive and specific method for determining the ABO blood type of semen samples obtained from sexual assault victims than existing methods, such as the conventional absorption-elution and classical hemagglutination-inhibition tests.  相似文献   
174.
This report contains the results of two population studies on the X chromosome STR HumHPRTB carried out in a Northern and a Southern region of Germany. The numbers of unrelated individuals were 443 and 335, respectively. Eight alleles (alleles 9 to 16) were found. In female individuals 29 different genotypes were encountered. In German populations the HumHPRTB STR was characterized by the following data: PIC = 0.750; HET = 0.769: MEC = 0.556. Allele distribution met the Hardy-Weinberg expectations. The Northern and Southern populations did not show any significant differences.  相似文献   
175.
We report a fatal case of death due to unusual aspiration of sardine fry in an elderly Japanese man with lung cancer. The cause of death was sudden respiratory arrest while eating. Autopsy revealed peculiar materials with cell nests and pigmented particles, together with striated muscle and skin, in the ectatic bronchioles of the left lower lobe. Serial histologic sections suggested that the structures observed were the eyeballs of small animals that appeared to have been inhaled. The patient had habitually eaten sardine fry and rice gruel, which were also detected in the gastric contents. Therefore, the eyes were considered to be those of the fry, which is a popular food item in Japan. This was confirmed by histologic examination of fry that were obtained commercially.  相似文献   
176.
This study compares the identifying characteristics between the impressions made with original Chinese seals and photopolymer replicate seals, and between the impressions made with two photopolymer replicate seals that originate from one single negative. Various seal materials common to the Chinese community such as cow's horns and ivory are employed. Other than the common factors such as different incident angle upon imprinting or different degree of inking that constitute the natural variation in impressions, the physical changes of the seal materials with temperature will be considered. This study concludes that photopolymer replicate seal impressions can be differentiated from the originals in respect to print density and stroke morphology, but it is very difficult to differentiate between two photopolymer replicate seal impressions with the same origin. This study also proposes a simple method for the examination of forged Chinese seal impressions.  相似文献   
177.
A high-density aqueous salt solution for the preparation of density gradients is presented. It has been used successfully by the authors in forensic soil analysis. It has a density range that allows for the separation of a soil specimen's heavy mineral components. It has no odor or toxic fumes, which eliminates the need to use a hood during preparation, and is far superior to the organic liquids normally used to prepare density gradients. This liquid should cause many forensic scientists to reexamine their attitudes towards using density gradients in forensic soil casework.  相似文献   
178.
We have demonstrated that skin viability decreases at a measurable rate following death in an animal model. The decreased skin viability was measured by fluorescein diacetate and ethidium bromide using fluorescence emission spectroscopy. There is significant decrease of the fluorescence intensity of the fluorescein diacetate assay between the 1-4 h, the 6-24 h, and the >40 h time points postmortem. For times between 6-24 h and >40 h postmortem the ethidium bromide assay showed consistent and significant increases in signal. The fluorescence measurements in this study showed that under the experimental conditions the time of death could be determined for <4, 6-24, and >40 hapotmotrem. The application of these assays in the field will require further study of the environmental factors.  相似文献   
179.
Two cases of unexpected childhood death due to hemolytic uremic syndrome are reported. A 21-month-old girl who was discovered dead in bed following a short illness was found at autopsy to have overwhelming sepsis resulting from transmural colitis. Escherichia coli serotype 0157A was isolated from the intestine, and renal changes of hemolytic uremic syndrome were found. A 4-year-old girl died suddenly in hospital from intracranial hemorrhage while being treated for hemolytic uremic syndrome-related renal failure. Culture of urine and feces grew verocytotoxin producing E. coli. These cases demonstrate that hemolytic uremic syndrome may be a rare cause of unexpected childhood death and that the diagnosis may not be established prior to autopsy. Postmortem culture of tissues and fluids in cases of suspected sepsis in children may be essential in establishing this diagnosis, because histologic evaluation may be compromised by profound sepsis and tissue putrefaction. Accuracy in diagnosis may have significant public health and medicolegal consequences.  相似文献   
180.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号