全文获取类型
收费全文 | 6655篇 |
免费 | 525篇 |
国内免费 | 436篇 |
出版年
2023年 | 74篇 |
2022年 | 103篇 |
2021年 | 152篇 |
2020年 | 208篇 |
2019年 | 238篇 |
2018年 | 282篇 |
2017年 | 163篇 |
2016年 | 205篇 |
2015年 | 204篇 |
2014年 | 393篇 |
2013年 | 444篇 |
2012年 | 309篇 |
2011年 | 363篇 |
2010年 | 273篇 |
2009年 | 290篇 |
2008年 | 343篇 |
2007年 | 364篇 |
2006年 | 325篇 |
2005年 | 298篇 |
2004年 | 277篇 |
2003年 | 243篇 |
2002年 | 206篇 |
2001年 | 138篇 |
2000年 | 147篇 |
1999年 | 162篇 |
1998年 | 133篇 |
1997年 | 108篇 |
1996年 | 104篇 |
1995年 | 107篇 |
1994年 | 106篇 |
1993年 | 93篇 |
1992年 | 95篇 |
1991年 | 68篇 |
1990年 | 63篇 |
1989年 | 48篇 |
1988年 | 52篇 |
1987年 | 35篇 |
1986年 | 31篇 |
1985年 | 47篇 |
1984年 | 62篇 |
1983年 | 28篇 |
1982年 | 43篇 |
1981年 | 33篇 |
1980年 | 26篇 |
1979年 | 27篇 |
1978年 | 20篇 |
1977年 | 12篇 |
1976年 | 20篇 |
1975年 | 17篇 |
1974年 | 11篇 |
排序方式: 共有7616条查询结果,搜索用时 234 毫秒
31.
A total of 627 cattle representing seven breeds from south central Nebraska, USA were tested for 37 BoLA antigens which behave as products of 37 distinct alleles of the class I BoLA-A locus. Four antigens were absent from all breeds tested. The other antigens showed marked and statistically significant differences in breed distribution. There was no evidence for blank (null) alleles. The number of alleles in each breed ranged from 10 to 20. The Hereford and Simmental populations tested were less polymorphic than the Angus, Brown Swiss, Charolais, Gelbvieh and Limousin populations. 相似文献
32.
Hiroshi Suzuki Hideaki Taguchi Kazuko Nishimura Makoto Miyaji Akira Nakamura Hironori Nakajima 《Mycopathologia》1988,104(1):7-17
Summary The authors succeeded in establishing a murine model of systemic candidiasis being disseminated from the primary gastrointestinal lesions caused by oral inoculation of Candida albicans. Using this model, an attempt was made for detecting the Candida antigen by enzyme-linked immunosorbent assay using avidin-biotin (AB-ELISA) from the serum of infected mice.Gastrointestinal candidiasis was formed in all of the 20 mice treated with the drugs (antibiotics, antineoplastic agents, hydrocortisone, etc.) and inoculated orally with C. albicans. Fourteen of these mice suffered from submucosal candidiasis, and C. albicans was cultured from the visceral organs in 12 of them. The assay by AB-ELISA was able to detect 1.0 ng/ml Candida mannan in the mouse serum. The Candida antigen was detected in the sera of 11 of the 14 mice with submucosal candidiasis. However, the antigen could not be detected in the sera of the 6 mice with intramucosal candidiasis.The assay by AB-ELISA is more sensitive and specific for the diagnosis of systemic candidiasis than other serological assays. 相似文献
33.
John M. Fairbrother Réal Lallier Linda Leblanc Mario Jacques Serge Larivière 《FEMS microbiology letters》1988,56(3):247-252
Abstract The production of fimbrial antigen F165 by Escherichia coli strains was found to be dependent on the composition of the culture medium and was repressed in the presence of alanine or high levels of glucose, in anaerobic conditions or at growth temperatures of lower than 37°C. Optimal F165 production was found on a minimal medium containing 1% (w/v) casamino acids (MD-1). F165 antigen was isolated from bacteria by mechanical shearing, precipitated with ammonium sulfate, and purified by deoxycholate treatment and gel filtration on Superose 12. The purified fimbriae retained their native morphology as observed by electron microscopy and consisted of two separate protein subunits with apparent molecular weights of 17 500 and 19 000 on sodium dodecyl sulfate-polyacrylamide gels. 相似文献
34.
M. Wachsman L. Aurelian J. C. R. Hunter M. E. Perkus E. Paoletti 《Bioscience reports》1988,8(4):323-334
We studied the effect of the temporal regulation of herpes simplex virus (HSV) type 1 glycoprotein D (gD-1) expression in Ia+ epidermal cells (EC) and macrophages on virus specific immunity and protection from HSV-2 challenge. gD-1 was expressed on the surface of cells infected with a vaccinia recombinant containing gD-1 under the control of an early vaccinia virus promoter (VP176). It was not expressed in cells infected with a recombinant (VP254) in which gD-1 is controlled by a late vaccinia virus promoter. BALB/c mice immunized with both recombinants seroconverted to HSV-2 as determined by neutralization. However, HSV specific delayed type hypersensitivity (DTH) responses were significantly (p<0.025) higher in VP176 than VP254 immunized animals. Both VP176 and VP254 immunized mice were protected from severe neurological disease due to HSV-2 challenge at 14 days post immunization, but long term protection was observed only in VP176 immunized mice. 相似文献
35.
36.
A gentle method for the isolation of nuclei from developing silk glands ofBombyx mori has been standardized. The nuclei, whether isolated or directly visualizedin situ within the silk glands, exhibit complex morphology. The nuclei occupy almost the entire volume of the gigantic silk gland
cells. Although the isolated nuclei still retain their ramified morphology, being polyploid they are fragile and often become
fragmented. The histone and low-salt-extractable proteins from nuclei isolated from the middle and posterior silk glands on
different days of the fourth and fifth instars of larval development have been analysed. The histones did not show any stage-
or tissue-specific variations whereas the low-salt-extractable proteins showed some developmental stage specific variation.
Using the antibody raised against one such protein, its absence in the early stage of development has been confirmed by Western
blotting techniques. This developmental stage specific protein may be functionally linked to some activities responsible for
boosting up the production of silk or silk-related proteins during the fifth instar of larval development. 相似文献
37.
38.
Chika Kawashima Koji Terayama Masayuki II Shogo Oka Toshisuke Kawasaki 《Glycoconjugate journal》1992,9(6):307-314
The properties of a rat brain glucuronyltransferase, which is presumed to be associated with the biosynthesis of the HNK-1 epitope on sulfoglucuronyl glycolipids, are described. The enzyme required divalent cations for reaction, with maximal activity at 10mm Mn2+, and exhibited a dual optimum at pH 4–5 and pH 6 depending upon the buffer used, with the highest activity at pH 4.5 in MES buffer. This enzyme strictly recognized the Gal1-4GlcNAc terminal structure, and was highly specific for neolacto (type 2) glycolipids as acceptor. The enzyme was localized specifically in the brain, and was barely detected in other issues, including the thymus, spleen, liver, kidney, lung, and sciatic nerve fibres. Phosphatidylinositol and phosphatidylserine increased the enzymatic reaction 4.4- and 2.3-fold, respectively, whereas phosphatidylcholine slightly decreased the rate.Abbreviations GlcA
glucuronic acid
- Lc-PA14
lactotetraose-phenyl-C14H29
- nLc-PA14
neolactotetraose-phenyl-C14H29
- nLcOse4-Cer
neolactotetraosylceramide
- NP-40
Nonidet P-40
- PC
phosphatidylcholine
- PE
phosphatidylethanolamine
- PI
phosphatidylinositol
- PS
phosphatidylserine
- SGGL
sulfoglucuronyl glycolipid 相似文献
39.
Kelly K. Hunt Masahiko Shibata Rishab K. Gupta Donald L. Morton 《Cancer immunology, immunotherapy : CII》1992,34(6):377-382
Summary We developed a high-titer polyclonal antiserum to a glycoprotein tumor-associated antigen (TAA) by immunization of a baboon with the purified glycoprotein antigen. The baboon serum was fractionated into IgG and IgM components by DEAE Affi-Gel blue chromatography. The ability of the baboon IgM anti-TAA antibody to effect tumor cell lysis in the presence of complement was tested using a chromium-release assay. The baboon antibody was able to lyse melanoma target cells (20.8%–71.4% cytolysis), breast carcinoma cells (36.5%–38.9% cytolysis), and a neuroblastoma cell line (35.5% cytolysis) in the presence of complement but did not effect significant lysis of autologous lymphoblastoid cell lines (4.9% cytolysis) or peripheral blood lymphocytes from healthy volunteers (12.6% cytolysis). Cytolysis of melanoma target cells was completely inhibited by preabsorption of the IgM anti-TAA antibody with UCLA-SO-M14 (M14) cells and partially inhibited by preabsorption with several other melanoma cell lines. There was no significant inhibition of tumor cell lysis after preabsorption of the antibody with lymphoblastoid cell lines. Complement-dependent lysis of M14 targets could be blocked by addition of the purified antigen to the antibody prior to incubation with the tumor cells. Our results suggest that the glycoprotein TAA resides on the tumor cell surface and that the baboon IgM anti-TAA antibody recognizes the antigen on the cell surface and is able to fix complement and effect the lysis of the tumor cells. 相似文献
40.
Peter Schlag Maria Manasterski Thomas Gerneth Peter Hohenberger Margret Dueck Christian Herfarth Winfrid Liebrich Volker Schirrmacher 《Cancer immunology, immunotherapy : CII》1992,35(5):325-330
Summary A group of 23 colorectal cancer patients were treated by a new type of active specific immunotherapy (ASI) following complete surgical resection of liver metastases (R0 resection). For ASI treatment we used a vaccine consisting of 1 × 107 autologous, irradiated (200 Gy) metastases-derived tumor cells incubated with 32 hemagglutination units (HU) of Newcastle disease virus (NDV). The adjuvant vaccine therapy was started 2 weeks after surgery and was repeated five times at 14-days intervals followed by one boost 3 months later. The delayed-type hypersensitivity (DTH) skin reactions to the vaccine were measured as well as the DTH reactions to a challenge test of 1 × 107 non-virus-modified autologous tumor cells from liver metastases or 1 × 107 autologous normal liver cells. In addition 32 HU NDV alone and a standard antigen test (Merieux test) were applied pre- and post-vaccination. The vaccination was well tolerated. In 13 of 23 patients an increasing reactivity against the vaccine was observed during the vaccination procedure. Nine patients (40%) experienced an increased DTH reactivity against autologous tumor cells following vaccination, while 17% or fewer showed an increased reactivity to Merieux test antigens, NDV, or normal liver cells. The increased antitumor response was not correlated to responsiveness to NDV alone, autologous liver cells, enzymes and culture medium used for vaccine preparation or standard antigens (Merieux test). After a follow-up of at least 18 months 61% of the vaccinated patients developed tumor recurrence in comparison to 87% of a matched control groups from the same institution that had been only surgically treated. The results of this phase II trial are encouraging and should stimulate further prospective randomized studies. 相似文献