全文获取类型
收费全文 | 3468篇 |
免费 | 28篇 |
专业分类
各国政治 | 164篇 |
工人农民 | 26篇 |
世界政治 | 479篇 |
外交国际关系 | 439篇 |
法律 | 1831篇 |
中国共产党 | 71篇 |
中国政治 | 210篇 |
政治理论 | 200篇 |
综合类 | 76篇 |
出版年
2021年 | 25篇 |
2018年 | 22篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 21篇 |
2014年 | 110篇 |
2013年 | 27篇 |
2012年 | 200篇 |
2011年 | 205篇 |
2010年 | 91篇 |
2009年 | 98篇 |
2008年 | 219篇 |
2007年 | 250篇 |
2006年 | 214篇 |
2005年 | 216篇 |
2004年 | 170篇 |
2003年 | 162篇 |
2002年 | 188篇 |
2001年 | 143篇 |
2000年 | 158篇 |
1999年 | 52篇 |
1998年 | 13篇 |
1997年 | 16篇 |
1996年 | 26篇 |
1995年 | 16篇 |
1994年 | 37篇 |
1993年 | 13篇 |
1992年 | 21篇 |
1991年 | 32篇 |
1990年 | 24篇 |
1989年 | 21篇 |
1988年 | 104篇 |
1987年 | 24篇 |
1986年 | 26篇 |
1985年 | 27篇 |
1984年 | 27篇 |
1983年 | 21篇 |
1982年 | 17篇 |
1981年 | 33篇 |
1980年 | 28篇 |
1979年 | 32篇 |
1977年 | 41篇 |
1976年 | 32篇 |
1973年 | 12篇 |
1964年 | 27篇 |
1963年 | 24篇 |
1962年 | 41篇 |
1961年 | 18篇 |
1960年 | 22篇 |
1959年 | 29篇 |
排序方式: 共有3496条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
Allele frequencies for the loci HLA-DQA1, LDLR, GYPA, HBGG, D7S8, GC, and D1S80 were determined for a sample population of unrelated individuals from Slovenia. All loci meet Hardy-Weinberg expectations, except the loci GYPA (p = 0.041) and D1S80 (p = 0.009). There is little evidence for association of alleles among the seven loci. Only one out of 21 pairwise comparisons demonstrated departures from independence (HLA-DQA1/HBGG, p = 0.008). The allelic frequency data generally are similar to that of U.S. Caucasians. 相似文献
135.
136.
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
137.
138.
Regular consumption of cannabis can easily be detected by examination of hair for tetrahydrocannabinol, cannabinol, and cannabidiol. Although several studies have demonstrated that after contamination with smoke or treatment with THC containing shampoos THC is not detectable, or only in small traces, the detection of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH) should be offered to prove the consumption and metabolisation of THC. Up to now this confirmation was only available using tandem MS techniques combined with negative chemical ionisation. A new method using a normal quadrupole GC/MS is described. The lack of expensive instruments has to be paid for by a costly and time consuming extraction and clean-up. After the sample has been digested by 2 M NaOH at 95 degrees C and the neutralised liquid has been extracted with a mixture of n-hexane and ethyl acetate the dried residue is reconstituted in acetonitrile-methanol-0.01 M sulfuric acid (49:21:30, v/v/v) and the cannabinoids separated by HPLC. Each fraction is collected over 1 min. Another extraction with n-hexane-ethyl acetate is followed by evaporation, derivatisation, and GC/MS determination. The calibration with THCCOOH spiked hair led to a LOD of 0.3 pg/mg and a LOQ of 1.1 pg/mg. 相似文献
139.
Computer-assisted facial image identification system using a 3-D physiognomic range finder 总被引:3,自引:0,他引:3
Yoshino M Matsuda H Kubota S Imaizumi K Miyasaka S 《Forensic science international》2000,109(3):225-237
This system consists of a 3-D physiognomic range finder and a computer-assisted facial image superimposition unit. The 3-D range finder is composed of a detector for measuring facial surface and its control computer. The detector has two sinusoidal grating projection devices and two CCD cameras. The computer-assisted facial image superimposition unit consists of a host computer including a proprietary software, a flat surface color display and a color image scanner for inputting 2-D facial images of a criminal. The 3-D facial shape and texture of a suspect is obtained by using the range finder. To make the comparison between the 3-D facial image and the 2-D facial image, the 3-D facial image is first reproduced on a display of the host computer from a MO disk and then the 2-D facial image is taken with the color image scanner and reproduced on the display. The 3-D facial image is exactly adjusted to match the orientation and size of the 2-D facial image under the fine framework mode, and then the fine framework mode of 3-D facial image is converted to the fine texture image. The shape and positional relationships of facial components between the 3-D and 2-D facial images are examined by the fade-out or wipe image mode. The distance between the selected two points and angle among the selected three points on the 3-D and 2-D facial images are automatically measured for the assessment of anthropometrical data between both images. For evaluating the fit between the anthropometrical points on the 3-D and 2-D facial images, the reciprocal point-to-point difference between both images is compared. 相似文献
140.
A sandwich enzyme immunoassay for pulmonary surfactant protein D and measurement of its blood levels in drowning victims 总被引:1,自引:0,他引:1
A sensitive sandwich enzyme immunoassay for human pulmonary surfactant protein D (SP-D) was developed and used to examine the blood SP-D levels of drowning victims. Human SP-D was purified from amniotic fluid by chromatographic methods, and an antibody against human SP-D was prepared. A polystyrene ball coated with anti-SP-D IgG was incubated with purified human SP-D, and then with anti-SP-D Fab'-peroxidase conjugate. Peroxidase activity bound to the polystyrene ball was assayed by fluorometry using 3-(4-hydroxyphenyl)propionic acid as the hydrogen donor. The detection limit of human SP-D was 5.2 pg per assay tube. Examination of cross-reactions of this sandwich enzyme immunoassay with proteins from other human organs showed it to be highly specific for lung, and Northern blot analysis detected specific SP-D mRNA expression only in lung. The SP-D concentration of normal human serum was 6.4+/-2.7 (mean+/-S.D.) ng ml(-1) (n=20). The recovery rates of 0.52 ng and 5.2 ng SP-D added to 5 microl normal human serum were 93.6+/-2.7% and 93.6+/-6.1%, respectively. Blood SP-D levels of victims from the saltwater drowning group (n=14) revealed higher concentrations (105.8+/-53.7 ng ml(-1)), while freshwater drowning victims (n=12) were estimated to be 74.1+/-43.9 ng ml(-1). The SP-D levels of 15 subjects who died of hemorrhage (n=5), heart failure (n=8), traumatic shock (n=1), and electrocution (n=1) were lower (22.0+/-8.5 ng ml(-1)), and those of asphyxia victims (n=10) were slightly higher (36.2+/-17.1 ng ml(-1)) than those of other causes of death, except for drowning. These results suggest that in drowning victims, SP-D flowed into the systemic circulation by physiological and physical mechanisms, and the differences of blood SP-D levels between saltwater drowning and freshwater drowning victims are presumed to be influenced by the type of agony and/or the length of survival time in water. 相似文献