全文获取类型
收费全文 | 4569篇 |
免费 | 290篇 |
出版年
2022年 | 22篇 |
2021年 | 42篇 |
2020年 | 21篇 |
2019年 | 33篇 |
2018年 | 47篇 |
2017年 | 48篇 |
2016年 | 82篇 |
2015年 | 142篇 |
2014年 | 141篇 |
2013年 | 283篇 |
2012年 | 281篇 |
2011年 | 286篇 |
2010年 | 179篇 |
2009年 | 168篇 |
2008年 | 268篇 |
2007年 | 263篇 |
2006年 | 288篇 |
2005年 | 264篇 |
2004年 | 275篇 |
2003年 | 254篇 |
2002年 | 240篇 |
2001年 | 106篇 |
2000年 | 80篇 |
1999年 | 81篇 |
1998年 | 57篇 |
1997年 | 54篇 |
1996年 | 55篇 |
1995年 | 53篇 |
1994年 | 37篇 |
1993年 | 35篇 |
1992年 | 74篇 |
1991年 | 65篇 |
1990年 | 56篇 |
1989年 | 45篇 |
1988年 | 38篇 |
1987年 | 38篇 |
1986年 | 40篇 |
1985年 | 33篇 |
1984年 | 34篇 |
1983年 | 21篇 |
1982年 | 24篇 |
1981年 | 33篇 |
1980年 | 24篇 |
1979年 | 21篇 |
1978年 | 22篇 |
1977年 | 19篇 |
1976年 | 14篇 |
1975年 | 13篇 |
1974年 | 9篇 |
1970年 | 7篇 |
排序方式: 共有4859条查询结果,搜索用时 15 毫秒
81.
Characterization of the endosymbiont of a deep-sea bivalve, Calyptogena soyoae. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have purified DNA from gill tissue of a marine bivalve, Calyptogena soyoae, collected from the deep-sea cold seep communities in Sagami Bay, Japan. An rRNA gene was amplified, cloned, and sequenced. In situ hybridization revealed that the sequence is that of a bacterial endosymbiont within the gill of C. soyoae. 相似文献
82.
Keiko Yamamura Tsunehisa Sakurai Kohji Yano Takashi Osada Toshitaka Nabeshima 《Microbiology and immunology》1995,39(11):895-896
To examine the efficacy of sisomicin (SISO) incorporated into fibrin glue (FG) for the prevention of graft infection in animal models, the susceptibility to infection of Dacron grafts (control) and SISO-FG Dacron grafts following the inoculation of Staphylococcus aureus or S. epidermidis was compared. The results showed that SISO-FG Dacron grafts displayed resistance to graft infection. 相似文献
83.
Tomohiro Kato Keiko Sato Satoshi Suzuki Hiroko Sasakawa Manae Kurokawa Kusuki Nishioka Kazuhiko Yamamoto 《Molecular biology reports》1995,21(3):141-146
To promote application of a single chain variable region fragment (sFv) in immunoglobulins, a sFv gene was connected to an IgG1 Fc gene, designated as a sFvc gene, and used for transfection of Sp2/0. As a result, the sFvc protein was found to be secreted in a dimeric form. It is thus felt that the sFvc protein, which mimicks the shape of a naturally occurring antibody, can be simple and useful to reproduce divalency and Fc-associated effecter functions as seen in a natural antibody.Abbreviations Abbreviations sFv
single chain variable region fragment
- Fc
constant region of immunoglobulin
- sFvc
single chain variable region fragment with an Fc region 相似文献
84.
Immunochemical characterisation and epitope mapping of a novel fimbrial protein (Pg-II fimbria) of Porphyromonas gingivalis 总被引:2,自引:0,他引:2
Tomohiko Ogawa Kenji Yasuda Keiko Yamada Hideharu Mori Keiko Ochiai Mamoru Hasegawa 《FEMS immunology and medical microbiology》1995,11(3):247-255
Abstract Mouse monoclonal antibody (mAb) Pgf-II specific for a 72-kDa major cell-surface protein (72K-CSP) derived from Porphyromonas gingivalis OMZ 409 was prepared. Immunoblotting analysis revealed that mAb Pgf-II reacted with 72K-CSP but not with 41-kDa fimbrial subunit protein (41K-fimbrilin) derived from P. gingivalis 381. Electron microscopic observation revealed that P. gingivalis OMZ 409 possessed peritrichous, thin fimbriae on their surface. Immunogold electron microscopy also demonstrated that mAb Pgf-II bound to the 72K-CSP examined with the gold particles arranged along the fibril array originating from the cell surface of the bacteria. These findings suggested that P. gingivalis 72K-CSP was identifiable as another fimbriae (termed Pg-II fimbriae) different from the fimbriae (termed Pg-I fimbriae) composed of a 41K-fimbrilin. Using multipin peptide synthesis technology, 102 sequential overlapping peptides covering the entire 514 amino-acid stretch of Pg-II fimbriae were synthesised. Seven immunodominant regions within Pg-II fimbrial protein molecule, which definitely reacted with the serum of patients with periodontal diseases, were detected. 相似文献
85.
The nucleotide sequence of a full length cDNA of delta-crystallin mRNA from chicken lens has been determined using a delta-crystallin cDNA clone (pB delta 11), which represents the mRNA sequence of 1530 nucleotides from the poly(A) junction but does not contain the 5'-terminal sequence of 44 nucleotides of the mRNA. The 5'-terminal sequence of the mRNA, absent in the cDNA clone, has been determined with a stretch of cDNA sequence by the primer extension procedure. The amino acid sequence deduced from the nucleotide sequence is consistent with the amino acid sequences of several tryptic peptides, the total amino acid composition, and the mol. wt. of delta-crystallin estimated by SDS-polyacrylamide gel electrophoresis. The computer-assisted analysis predicts high alpha-helical content throughout the polypeptide. Sequence analyses have revealed that gene 1 encodes the mRNA from which the cDNA clone was derived. 相似文献
86.
S Nakamura S Sakata T Komaki N Kojima K Kamikubo S Miyazaki K Yasuda H Tsukada S Shiraki K Miura 《Endocrinologia japonica》1984,31(6):675-679
We measured the levels of serum thyroglobulin (Tg) in 52 pregnant females at various stages and compared them with those of 15 age-matched nonpregnant females. Serum Tg was measured by a solid-phase immunoradiometric assay. In pregnant females, mean serum Tg levels at the first, second, early third, and late third trimesters were 8.4 (range; 1.3-18.0), 9.2 (1.7-25.6), 10.1 (1.8-22.8), and 12.1 ng/ml (5.3-25.2), respectively. The statistical comparison was made after logarithmic transformation of the data. The mean value only at the late third trimester was significantly higher than that of controls (mean; 6.0 ng/ml, range; 1.5-23.6), but each value was within the normal range. Although serum Tg levels have been reported to be high at the end of pregnancy, our results indicate that the Tg levels in females could be clinically interpreted without regard to the coexistence of pregnancy. 相似文献
87.
S Kanegasaki Y Kojima M Matsuura J Y Homma A Yamamoto Y Kumazawa K Tanamoto T Yasuda T Tsumita M Imoto 《European journal of biochemistry》1984,143(2):237-242
Lipid A analogues were chemically synthesized based on the model structure recently revised, and biological activities of the analogues were tested. The analogue, (beta-1,6)-linked glucosamine disaccharide carrying ester-bound 3-hydroxytetradecanoic acids at 3 and 3' position of reducing and nonreducing glucosamine in addition to amide-bound 3-hydroxytetradecanoic acids and glycosidic-linked and ester-linked phosphate groups, showed much stronger activities for mediator inducing and immunomodulating as well as endotoxic activities than those exhibited by the previously synthesized analogues based on the old model. Among the activities tested, induction of interferon and tumor necrosis factor as well as mitogenicity, adjuvanticity and pyrogenicity were, however, not expressed so strongly as natural lipid A used as controls. In contrast, the analogue exhibited comparable activities to those of control lipid A in the test of lethal toxicity to mice and gelating activity of Limulus amebocyte lysate. Other synthetic analogues carrying a phosphate group showed comparable, slightly stronger or weaker activities depending on the test, but nonphosphorylated analogue exhibited no apparent or only very weak activities. 相似文献
88.
Occurrence of a factor(s) which can selectively inhibit ribosomal RNA synthesis in isolated neurula cells of Xenopus laevis was examined in oocytes, unfertilized eggs, and embryos of Xenopus laevis. It was found that acid-soluble materials from full-sized oocytes, white-banded mature oocytes, unfertilized eggs, and pregastrular embryos were all active in significantly reducing the relative ratio of the [3H]uridine incorporation into 18S and 28S ribosomal RNA to that into 4S RNA from the control value. These results suggest that the inhibitor appears in the terminal step of oogenesis and, hence, may be assumed as a maternal regulator. 相似文献
89.
C-Terminal peptidyl-L-proline hydrolase activity of Aspergillus acid carboxypeptidase. 总被引:1,自引:0,他引:1
Aspergillus saitoi acid carboxypeptidase hydrolyzed C-terminal peptidyl-L-proline bonds and released the C-terminal proline from Z-Gly-Pro-Leu-Gly-Pro and Z-Gly-Pro at pH 3.3. Proline liberated by the enzymic reaction was measured by a sensitive colorimetric ninhydrin method in glacial acetic acid at 513 nm. A Km value of 1.0 mM and a kcat value of 0.09 s-1 for Z-Gly-Pro-Leu-Gly-Pro hydrolysis, and a Km value of 5.0 mM and a kcat value of 0.0045 s-1 for Z-Gly-Pro hydrolysis were calculated from Lineweaver-Burk plots. 相似文献
90.
Hydrophobic protein (H protein) was isolated from membrane fractions of Bacillus subtilis and constituted into artificial membrane vesicles with lipid of B. substilis. Glutamate was accumulated into the vesicle when a Na+ gradient across the membrane was imposed. The maximum effect of Na+ on the transport was achieved at a concentration of about 40 mM, while the apparent Km for Na+ was approximately 8 mM. On the other hand, Km for glutamate in the presence of 50 mM Na+ was about 8 μM. Increasing the concentration of Na+ resulted in a decrease in Km for glutamate, maximum velocity was not affected. The transport was sensitive to monensin (Na+ ionophore).Glutamate was also accumulated when pH gradient (interior alkaline) across the membrane was imposed or a membrane potential was induced with K+-diffusion potential. The pH gradient-driven glutamate transport was sensitive to carbonylcyanide m-chlorophenylhydrazone and the apparent Km for glutamate was approximately 25 μM.These results indicate that two kinds of glutamate transport system were present in H protein: one is Na+ dependent and the other is H+ dependent. 相似文献