全文获取类型
收费全文 | 322007篇 |
免费 | 21668篇 |
国内免费 | 61篇 |
专业分类
343736篇 |
出版年
2021年 | 2689篇 |
2020年 | 2211篇 |
2019年 | 2516篇 |
2018年 | 5457篇 |
2017年 | 5159篇 |
2016年 | 6655篇 |
2015年 | 7634篇 |
2014年 | 8923篇 |
2013年 | 12399篇 |
2012年 | 14898篇 |
2011年 | 14963篇 |
2010年 | 10110篇 |
2009年 | 8126篇 |
2008年 | 12858篇 |
2007年 | 13120篇 |
2006年 | 12347篇 |
2005年 | 11512篇 |
2004年 | 11332篇 |
2003年 | 10731篇 |
2002年 | 10342篇 |
2001年 | 11207篇 |
2000年 | 10821篇 |
1999年 | 8602篇 |
1998年 | 2826篇 |
1997年 | 2509篇 |
1996年 | 2314篇 |
1995年 | 2155篇 |
1992年 | 6596篇 |
1991年 | 6727篇 |
1990年 | 6582篇 |
1989年 | 6467篇 |
1988年 | 6022篇 |
1987年 | 5561篇 |
1986年 | 5091篇 |
1985年 | 5379篇 |
1984年 | 4316篇 |
1983年 | 3537篇 |
1982年 | 2416篇 |
1979年 | 3883篇 |
1978年 | 2992篇 |
1977年 | 2751篇 |
1976年 | 2693篇 |
1975年 | 3220篇 |
1974年 | 3533篇 |
1973年 | 3509篇 |
1972年 | 3057篇 |
1971年 | 2915篇 |
1970年 | 2494篇 |
1969年 | 2424篇 |
1968年 | 2279篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
861.
L S Naumov V K Numerov A N Bozhko A A Lushnikov V S Tiurim 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1977,(5):33-37
Bac. subtilis 168 (BD-25) cells were infected with DNA of plasmide R1drd19 isolated from E. coli strain; transformants resistant to streptomycin (500 microgram/ml) and kanamycin (40 microgram/ml) appeared with the frequency of 2.10(-6). These transformants retained resistance to the mentioned antibiotics stably. A satellite DNA peak was revealed in centrifugation in the density gradient of cesium chloride with ethidium bromide. It was possible to infect cells of Bac. subtilis 168 (BD-25) with plasmide DNA isolated from the transformants. Plasmide transduction with the aid of phages AR9 and PBSI multiplied on the transformant strains was also effected. Physico-chemical analysis of the transformed plasmide DNA was conducted; its molecular weight was determined. 相似文献
862.
V R Vukadinovi? L M Raki? 《Archives internationales de physiologie et de biochimie》1976,84(4):753-758
Vitamin B6 injected intraperitoneally into rats 400 mg/kg body weight, has produced a statistically significant decrease in GABA level concentrations in hippocampus and cerebellum. Cerebral cortex, caudate nucleus and thalamus have shown the decrease in GABA concentrations, but these changes were not statistically significant. No remarkable behavioural changes were noted under such circumstances. The possible functional meaning of these results is discussed in relation to the role of GABA distribution in different brain regions and development of convulsions. 相似文献
863.
M R Giovagnoli P Di Fraia A Manna V Marafini C Valli P Marchei A Vecchione 《The International journal of biological markers》1989,4(1):13-17
We tested the presence of tumour polypeptide antigen (TPA) in lower urinary tract cells from 59 workers exposed to known bladder carcinogens and from 30 control subjects. We then correlated immunocytological expression and serum TPA levels. Lower urinary tract cells from 31 subjects gave either moderately or strongly positive immunocytological stains. Five also had high serum TPA. The detection of TPA by cytology and in serum differed significantly in workers exposed to cancer agents and the control group. 相似文献
864.
Eriocaulon raipurense (Eriocaulaceae) is described and illustrated as a new species from Madhya Pradesh, India. The species is closely allied to E. hamiltonianum but differs in the size and apex of involucral bancts, white-pilose nature of floral bracts and colour of female petals. 相似文献
865.
866.
Characterization of transverse tubule membrane proteins: tentative identification of the Mg-ATPase 总被引:1,自引:0,他引:1
V R Okamoto M P Moulton E M Runte C D Kent H G Lebherz A S Dahms R A Sabbadini 《Archives of biochemistry and biophysics》1985,237(1):43-54
Vesiculated fragments of chicken skeletal muscle transverse tubule (TT) membranes were analyzed for their content of loosely associated and integral membrane proteins. Of particular interest was the identification of the magnesium-stimulated ATPase (Mg-ATPase), which is characteristically located in native isolated TT vesicles of chicken skeletal muscle [R. A. Sabbadini and V. R. Okamoto (1983) Arch. Biochem. Biophys. 223, 107-119]. A number of the proteins found in vesicular TT preparations were found to be extractable by a mild Triton-X100 treatment and were identified as aldolase, enolase, creatine kinase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and pyruvate kinase. Approximately 60% of TT-associated protein was extracted with Triton, resulting in a twofold enrichment of the Mg-ATPase. Concommitantly, one core integral membrane protein possessing a Mr of 102,000 was enriched, suggesting that it is responsible for the Mg-ATPase activity present in chicken skeletal muscle TT membranes. 相似文献
867.
Marie Lipoldová Helena Havelková Jana Badalová Jarmila Vojtíšková Lei Quan Magdaléna Krulová Yahya Sohrabi Alphons P. Stassen Peter Demant 《Cancer immunology, immunotherapy : CII》2010,59(2):203-213
Low infiltration of lymphocytes into cancers is associated with poor prognosis, but the reasons why some patients exhibit
a low and others a high infiltration of tumors are unknown. Previously we mapped four loci (Lynf1–Lynf4) controlling lymphocyte infiltration of mouse lung tumors. These loci do not encode any of the molecules that are involved
in traffic of lymphocytes. Here we report a genetic relationship between these loci and the control of production of IFNγ
in allogeneic mixed lymphocyte cultures (MLC). We found that IFNγ production by lymphocytes of O20/A mice is lower than by
lymphocytes of OcB-9/Dem mice (both H2
pz
) stimulated in MLC by irradiated splenocytes of C57BL/10SnPh (H2
b
) or BALB/cHeA (H2
d
) mice, or by ConA. IFNγ production in MLCs of individual (O20 × OcB-9)F2 mice stimulated by irradiated C57BL/10 splenocytes and genotyped for microsatellite markers revealed four IFNγ-controlling
loci (Cypr4-Cypr7), each of which is closely linked with one of the four Lynf loci and with a cluster of susceptibility genes for different tumors. This suggests that inherited differences in certain
lymphocyte responses may modify their propensity to infiltrate tumors and their capacity to affect tumor growth. 相似文献
868.
Histological and electron microscopy findings suggesting the effect of monochromatic coherent polarized red light on zymosan arthritis in rats are presented. The data obtained have confirmed that treatment of inflamed joints with laser rays exerts an evident therapeutic effect which is determined by activated function of macrophages and fibroblasts of the synovial membrane, resulting in a more rapid change of inflammation phases. Analysis of the cases where the rats were treated with ordinary red light has revealed no essential differences in the joints of the control and irradiated groups. 相似文献
869.
B S Kasavina Iu F Ma?chuk T V Ukhina 《Biulleten' eksperimental'no? biologii i meditsiny》1983,95(3):44-45
Activity of phosphodiesterases disintegrating cAMP and cGMP in the cornea, sclera and ciliary body was investigated in health and in different stages of experimental herpetic keratitis. The problems concerning the role of the cyclase system in the pathogenesis of herpetic keratitis and the possibility of applying some of the drugs to the disease treatment are discussed. 相似文献
870.
L A Novikova S M Dracheva A S Zubatov V N Luzikov 《Biokhimii?a (Moscow, Russia)》1982,47(8):1401-1408
The proteins of submitochondrial particles solubilized with 0.1% Triton X-100 were separated by polyacrylamide gel electrophoresis. Hydrolysis of several proteinase substrates was registered directly in the gel after completion of electrophoresis. According to the data obtained the inner mitochondrial membrane contains one or two enzymes which catalyze hydrolysis of cytochrome c as well as one or two enzymes splitting synthetic substrate of trypsin-like proteinases, e. g. N-alpha-benzoyl-L-arginine-p-nitroanilide (BAPA) and N-alpha-benzoyl-L-arginine-beta-naphthylamide (BANA). Submitochondrial particles were shown to catalyze hydrolysis of 3H-labelled cytochrome c. This activity is suppressed by the same inhibitors as the hydrolysis of mitochondrial translation products, i. e. phenyl-methylsulfonylfluoride, p-chloromercuribenzosulfonate, leupeptin and antipain. Presumably these two processes are catalyzed by the same enzyme localized in the inner mitochondrial membrane. Physiological functions of BAPA- and BANA-hydrolyzing enzyme(s) are still unclear. 相似文献