全文获取类型
收费全文 | 11907篇 |
免费 | 807篇 |
出版年
2022年 | 66篇 |
2021年 | 149篇 |
2020年 | 83篇 |
2019年 | 107篇 |
2018年 | 196篇 |
2017年 | 136篇 |
2016年 | 221篇 |
2015年 | 324篇 |
2014年 | 396篇 |
2013年 | 665篇 |
2012年 | 615篇 |
2011年 | 667篇 |
2010年 | 366篇 |
2009年 | 372篇 |
2008年 | 629篇 |
2007年 | 598篇 |
2006年 | 540篇 |
2005年 | 541篇 |
2004年 | 552篇 |
2003年 | 499篇 |
2002年 | 528篇 |
2001年 | 375篇 |
2000年 | 383篇 |
1999年 | 315篇 |
1998年 | 157篇 |
1997年 | 121篇 |
1996年 | 123篇 |
1995年 | 126篇 |
1994年 | 98篇 |
1993年 | 87篇 |
1992年 | 241篇 |
1991年 | 259篇 |
1990年 | 213篇 |
1989年 | 216篇 |
1988年 | 168篇 |
1987年 | 145篇 |
1986年 | 124篇 |
1985年 | 137篇 |
1984年 | 121篇 |
1983年 | 113篇 |
1982年 | 95篇 |
1981年 | 72篇 |
1980年 | 55篇 |
1979年 | 77篇 |
1978年 | 85篇 |
1977年 | 59篇 |
1976年 | 72篇 |
1975年 | 54篇 |
1973年 | 59篇 |
1971年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
61.
Experimental and clinical chronocardiology 总被引:2,自引:0,他引:2
Recent advances of the chronobiologic approach to experimental and clinical cardiology was reviewed. First, the maximum entropy method (MEM) was introduced as one of the statistical methods analyzing the circadian periodicity. The MEM power spectrum showed a remarkable resolution property. It will play an important role in chronocardiology in cooperation with the cosinor method. Secondly, recent investigations of the relationship between sleep states and cardiac arrhythmias were mentioned from the viewpoints of both experimental and clinical chronocardiology. Next, recent remarkable advance on myocardial ischemia was reviewed. A marked circadian rhythm in the frequency of myocardial infarction onset and sudden cardiac death has been observed. Lastly, a reference has been made to the recent development of ambulatory BP monitoring. A chronobiologic approach to the analysis of time-series data in cardiology will lead to many advantages in clinical practice. 相似文献
62.
63.
Hiroki Yamaue Hiroshi Tanimura Takuya Tsunoda Makoto Iwahashi Masaji Tani Mikiko Tamai Masaya Inoue 《Biotherapy》1990,2(3):247-259
The tumor-infiltrating lymphocytes (TILs) were cultured with interleukin 2 (IL-2) to induce the activated killer cells possessing autologous tumor-killing activity, and analysed their cell surface phenotypes and assessed anti-tumor killing activity. Furthermore, the activated TILs were transferred into 7 patients adoptively resulting in complete remission in a patient with pancreatic cancer and partial remission in another patient with gastric cancer.The cytotoxic activities of activated TILs at 3 weeks-incubation was 72 ± 15, 42 ± 26, 27 ± 21 and 25 ± 15% against K562, Daudi, KATO-III and autologous tumor, respectively. The negative selection method, indicated that the killer cells recognizing autologous tumor cells consisted of CD4- or CD8-positive T lymphocytes and CD16- or CD56-positive natural killer cells. The activated TILs could not only lyse cultured tumor cell lines, but also autologous tumor cells. 相似文献
64.
Kazuhisa Toyoda Takuya Sugahara Kunio Inouye Koji Yamada Sanetaka Shirahata Hiroki Murakami 《Cytotechnology》1990,3(2):189-197
An immunoglobulin (Ig) production stimulating factor (IPSF) for hybridomas was found in spent medium of the human B lymphoblastoid cell line, HO-323. The IPSF was purified by serial use of DEAE chromatography, ultrafiltration, gel filtration and HPLC-DEAE chromatography. Purified IPSF was estimated to be a 410 k macro molecule by gel filtration, and contained three types of isomers which were separated from each other by native polyacrylamide gel electrophoresis. All of the isomers were, however, assumed to have the same protein components by SDS polyacrylamide gel electrophoresis.The IPSF was effective for human-human and mouse-mouse hybridomas producing IgM, but not for IgG producers in the experimental condition used here. Human-human hybridoma HF10B4, cultured in IPSF-containing medium, produced 20 times more IgM than in IPSF-free medium under serum-free conditions. The IPSF showed very little proliferation stimulating activity on HF10B4 cells. 相似文献
65.
Rates of assembly and degradation of bacterial ice nuclei 总被引:6,自引:0,他引:6
N. M. Watanabe M. W. Southworth † G. J. Warren P. K. Wolber 《Molecular microbiology》1990,4(11):1871-1879
The kinetics of ice-nucleus assembly from newly synthesized nucleation protein were observed following induction of nucleation gene expression in the heterologous host Escherichia coli. Assembly was significantly slower for the small proportion of ice nuclei active above -4.4 degrees C; this was consistent with the belief that these nuclei comprise the largest aggregates of nucleation protein. The kinetics of nucleus degradation were followed after inhibiting protein synthesis. Nucleation activity and protein showed a concerted decay, indicating that most of the functional ice nuclei are in equilibrium with a single cellular pool of nucleation protein. A minority of the ice nuclei decayed much more slowly than the majority; presumably their nucleation protein was distinct either by virtue of different structure or different subcellular compartmentalization, or because of its presence in a metabolically distinct subpopulation of cells. 相似文献
66.
67.
Y Wataya T Hazawa K Watanabe Y Hirota A Yoshioka-Hiramoto 《Nucleic acids symposium series》1988,(19):53-55
The mechanism of intracellular deoxyribonucleoside-triphosphate (dNTP) imbalance death of mouse mammary tumor FM3A cells was studied. When the cells were exposed to 5-fluorodeoxyuridine, deoxyadenosine, or 2-chlorodeoxyadenosine, dNTP pool imbalance resulted. The imbalance was followed by DNA double strand breaks and subsequent cell death. The DNA double strand breaks have been directly examined by means of orthogonal-field-alternation gel electrophoresis (OFAGE). Fragmented DNA band appeared to be approximately 100-200 kb in size. 相似文献
68.
Rejection of B16 melanoma induced by expression of a transfected major histocompatibility complex class I gene. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Transfection of a functional major histocompatibility complex class I gene into certain tumor cells, induced by oncogenic viruses or chemical carcinogens, can effectively abrogate their tumorigenic activity. Since experimentally induced tumors possess strong tumor-specific transplantation antigens, expression of cell surface class I antigens may present the tumor cells to appropriate immune effector cells. Most spontaneously arising tumors do not possess tumor-specific transplantation antigens, and their tumorigenicity may not be affected by the expression of a transfected class I gene. We demonstrate that the poorly immunogenic B16-BL6 melanoma can be rendered nontumorigenic in syngeneic mice by the expression of the class I H-2K antigen but not the class II I-A antigen. Furthermore, the poorly tumorigenic, class I-expressing B16-BL6-transfected cells can effectively immunize syngeneic C57BL/6 mice against the highly tumorigenic, class I-deficient B16-BL6 parental cells. Our success in experimentally manipulating the tumorigenicity of a spontaneously derived neoplasm offers hope for a potential modality for the effective treatment of human cancer. 相似文献
69.
Nobutaka Fujii Akira Otaka Susumu Funakoshi Toshihiro Watanabe Hiromitsu Arai Kiyoshi Bessho Haruaki Yajima 《Journal of Protein Chemistry》1988,7(2):151-156
Treatment of a mixture of Cys(R)(O) and Cys(R) with an acid was found to generate cystine in fairly good yields, when suitable R, R, and an acid were selected. An unsymmetrical cystine peptide was prepared by treatment of a mixture of Z(OMe)-Cys(R) (0)-Ala-NH2 (R=Acm or MBzl) and Z(OMe)-Cys(MBzl)-Gly-OBzl with TFA or 1 M TFMSA/TFA.3 Oxytocin was obtained in an excellent yield by TFA treatment of the protected peptide containing Cys(Acm)(0) and Cys(MBzl). Thus, formation of the disulfide bond was found feasible at the position of Cys(R) (0).The following abbreviations are used Boc
t-butyloxycarbonyl
- Z(OMe)
p-methoxybenzyloxycarbonyl
- MBzl
p-methoxybenzyl
- Acm
acetamidomethyl
- Bzl
benzyl
- Ad
l-adamantyl
- tBu
t-butyl
- TFA
trifluoroacetic acid
- TFMSA
trifluoromethanesulfonic acid
- TMSOTf
trimethylsilyl trifluoromethane sulfonate 相似文献
70.
Effect of exogenous fatty acids on zygote formation in Saccharomyces cerevisiae was studied. Arachidonic and oleic acids considerably stimulated zygote formation, but other fatty acids tested, linoleic, linolenic, stearic and palmitic acids, did not. Pretreatment experiments with arachidonic acid showed that the stimulation of zygote formation by the fatty acid required the presence of mating pheromone.Abbreviations YPD
yeast-peptone-dextrose medium
- A530
absorbance at 530 nm 相似文献