全文获取类型
收费全文 | 772篇 |
免费 | 26篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 1篇 |
2018年 | 11篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 19篇 |
2012年 | 64篇 |
2011年 | 77篇 |
2010年 | 25篇 |
2009年 | 15篇 |
2008年 | 75篇 |
2007年 | 53篇 |
2006年 | 66篇 |
2005年 | 72篇 |
2004年 | 57篇 |
2003年 | 59篇 |
2002年 | 29篇 |
2001年 | 40篇 |
2000年 | 50篇 |
1999年 | 17篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1980年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1958年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有798条查询结果,搜索用时 31 毫秒
51.
The role of the cannabinoid system in morphine withdrawal was examined through long-term CB1 receptor antagonist administration in morphine pellet implanted rats. SR141716A chronic treatment (5mg/kg i.p. twice a day for four days) did not influence the development of tolerance to the morphine analgesic effect but significantly reduced the intensity of naloxone-induced opiate withdrawal in tolerant rats: Specifically there was a significant reduction in the number of digging, teeth chattering and penile licking and the incidence of diarrhoea while other signs such as writhing, head dog shakes and rearing were unaffected. These results suggest that the pharmacological treatment with SR141716A could be of some interest in ameliorating opiate withdrawal syndrome. 相似文献
52.
53.
M. Giovanna Parisi Matteo Cammarata Gigliola Benenati Giuseppina Salerno Valentina Mangano Aiti Vizzini Nicolò Parrinello 《Cell and tissue research》2010,341(2):279-288
The purification, cloning, sequencing, molecular properties and expression of a fucose-binding lectin from the serum of Dicentrarchus labrax (DlFBL) have been previously reported. We now describe the distribution and expression of DlFBL during fish ontogeny. Immunohistochemistry
and in situ hybridization assays were carried out at various developmental stages (from 10 days post-hatching larvae to juveniles).
Another fucose-binding lectin, similar to DlFBL in biochemical, immunochemical and agglutinating properties, was extracted
and purified from eggs and appeared to be localized in the embryo yolk sack residual. DlFBL was found in columnar and goblet
cells of the intestinal epithelium of larvae (from 20 days post-hatching) and juveniles and in parenchymal tissue of juveniles.
DlFBL mRNA and protein were detected in the intestinal epithelium and in hepatocytes. An amplification product from degenerate
primers indicates that lectin isotypes with DlFBL epitopes are expressed in eggs and embryos. Whether the lectin fraction
isolated from eggs and embryos includes DlFBL of maternal origin remains unclear. 相似文献
54.
55.
Gourlay LJ Sommaruga S Nardini M Sperandeo P Dehò G Polissi A Bolognesi M 《Protein science : a publication of the Protein Society》2010,19(12):2430-2439
Lipopolysaccharide (LPS) biosynthesis represents an underexploited target pathway for novel antimicrobial development to combat the emergence of multidrug‐resistant bacteria. A key player in LPS synthesis is the enzyme D ‐arabinose‐5‐phosphate isomerase (API), which catalyzes the reversible isomerization of D ‐ribulose‐5‐phosphate to D ‐arabinose‐5‐phosphate, a precursor of 3‐deoxy‐D ‐manno‐octulosonate that is an essential residue of the LPS inner core. API is composed of two main domains: an N‐terminal sugar isomerase domain (SIS) and a pair of cystathionine‐β‐synthase domains of unknown function. As the three‐dimensional structure of an enzyme is a prerequisite for the rational development of novel inhibitors, we present here the crystal structure of the SIS domain of a catalytic mutant (K59A) of E. coli D ‐arabinose‐5‐phosphate isomerase at 2.6‐Å resolution. Our structural analyses and comparisons made with other SIS domains highlight several potentially important active site residues. In particular, the crystal structure allowed us to identify a previously unpredicted His residue (H88) located at the mouth of the active site cavity as a possible catalytic residue. On the basis of such structural data, subsequently supported by biochemical and mutational experiments, we confirm the catalytic role of H88, which appears to be a generally conserved residue among two‐domain isomerases. 相似文献
56.
? Premise of the study: A new set of pomegranate microsatellites was selected and characterized to assess the level of genetic diversity among cultivars and wild genotypes. ? Methods and Results: Nine Simple Sequence Repeat (SSR) markers were obtained using the Microsatellite-AFLP technique and were successfully amplified in 34 genotypes belonging to Italian, Spanish, and Turkish germplasm collections. The number of alleles per locus ranged from 1 to 5, and the total number of alleles was 22. ? Conclusions: Because only a few codominant markers are available for this species, the newly identified SSRs will facilitate genetic diversity studies, fingerprinting, and mapping. In addition, the 9 loci successfully amplified in P. granatum var. nana. No cross transferability was observed for Cuphea micropetala and Lagerstroemia indica (Lythraceae). 相似文献
57.
58.
59.
We assessed the pollen hydration, the pollen germination, and the stigma papilla penetration of CROCUS VERNUS subsp. VERNUS (Iridaceae) after 2 h fumigations with O (3), NO (2), and CO gases within humidified (90 - 100 % RH) box experiments. When the pollen and the pistil were separately fumigated, the pollen retained the capacity to emit a tube which penetrated papilla, and the stigma papillae retained the receptivity; when the pistils were first pollinated and then fumigated, the capacity of pollen to hydrate was not affected, but the germination was significantly reduced. The vulnerability to gases became evident at 0.3 ppm O (3), 0.2 ppm NO (2), and 0.5 ppm CO. The inhibition curves as a function of the gas concentrations were of an exponential type, and they saturated at 2 ppm NO (2), 25 ppm CO, and 0.5 ppm O (3), with germination percentages of 17 %, 27 %, and 60 %, respectively. Both the pollen germination and the papilla penetration were fully restored by prolonging for 60 - 90 min the incubation at 90 - 100 % RH, after the cessation of fumigations. The vulnerability of the pollen-papilla system is discussed. 相似文献
60.
Stefano Biffani Corrado Dimauro Nicolò Macciotta Attilio Rossoni Alessandra Stella Filippo Biscarini 《遗传、选种与进化》2015,47(1)