全文获取类型
收费全文 | 2897篇 |
免费 | 150篇 |
专业分类
3047篇 |
出版年
2023年 | 4篇 |
2022年 | 15篇 |
2021年 | 32篇 |
2020年 | 16篇 |
2019年 | 29篇 |
2018年 | 33篇 |
2017年 | 34篇 |
2016年 | 58篇 |
2015年 | 89篇 |
2014年 | 109篇 |
2013年 | 145篇 |
2012年 | 194篇 |
2011年 | 200篇 |
2010年 | 121篇 |
2009年 | 109篇 |
2008年 | 167篇 |
2007年 | 204篇 |
2006年 | 171篇 |
2005年 | 189篇 |
2004年 | 182篇 |
2003年 | 170篇 |
2002年 | 169篇 |
2001年 | 51篇 |
2000年 | 40篇 |
1999年 | 53篇 |
1998年 | 30篇 |
1997年 | 28篇 |
1996年 | 24篇 |
1995年 | 38篇 |
1994年 | 23篇 |
1993年 | 25篇 |
1992年 | 38篇 |
1991年 | 37篇 |
1990年 | 26篇 |
1989年 | 27篇 |
1988年 | 23篇 |
1987年 | 19篇 |
1986年 | 7篇 |
1985年 | 17篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1973年 | 3篇 |
1968年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有3047条查询结果,搜索用时 0 毫秒
41.
ATP-dependent Sr2+ transport was examined in vitro using basolateral membrane (BLM) vesicles isolated from rat renal cortex to clarify the discrimination
mechanisms between strontium (Sr) and calcium (Ca) in renal tubules during reabsorption. ATP-dependent Sr2+ uptake and Ca2+ uptake were observed in renal BLM vesicles and were inhibited by vanadate. Hill plots indicate similar kinetic behavior for
Ca2+ and Sr2+ uptake. The apparentK
m andV
max of ATP-dependent Sr2+ uptake were both higher than those for Ca2+ uptake. ATP-dependent Sr2+ uptake by BLM vesicles diminished in the presence of 0.1 μM Ca2+ and was more markedly inhibited by 1 μM Ca2+. Hill plots of Sr2+ uptake data with and without 0.1 μM Ca2+ showed that the cooperative behavior of Sr2+ uptake was not changed by Ca2+. In the presence of 0.1 μM Ca2+, the affinity of the transport system for Sr2+ and the velocity of Sr2+ uptake in the BLM were both decreased. However, the rate of Ca2+ uptake was not diminished by Sr2+ concentrations of <1.6 μM. These results suggest that Ca2+ is preferentially transported in the renal cortex BLM when Ca2+ and Sr2+ are present at the same time. 相似文献
42.
Tadao Ohno Kaoru Saijo-Kurita Naoko Miyamoto-Eimori Tomoko Kurose Yasunobu Aoki Sigehiro Yosimura 《Cytotechnology》1991,5(3):273-277
We developed a simple method for freezing anchorage-dependent cells, including primary cultured rat liver parenchymal cells, without detaching the cells from the culture dish. The method consists of preculture of the cells to confluence, changing the growth medium to a conventional freezing medium, packaging in a container, and storage at –80°C. After thawing and changing the freezing medium to regular growth medium, cell growth was nearly identical to that of cells freshly seeded into a new dish. 相似文献
43.
An electrode system consisting of a basal-plane pyrolytic graphite (BPG) electrode and a porous nitrocellulose membrane filter to trap bacteria was used for the detection of bacteria in urine. The peak current of a cyclic voltammogram increased with increasing initial cell concentration of Escherichia coli in urine. Urine containing from 5 x 10(2) to 5 x 10(5) cells ml-1 was measured with this system. The susceptibility of bacteria to various antibiotics was also determined from the peak current. The minimum inhibitory concentration values obtained by the electrochemical method were in good agreement with those obtained by the conventional method. 相似文献
44.
45.
Kiyoshi Ohkawa Takashi Hatano Naoko Takizawa Kazue Shinmoto Kyosuke Yamada Makoto Matsuda Koji Takada Yutaka Tsukada 《In vitro cellular & developmental biology. Animal》1992,28(6):449-454
Summary A human yolk sac tumor cell line, TG1, which was established from a testicular yolk sac tumor, was found to replicate continuously
in a chemically defined medium supplemented with Na2SeO3 (ISRPMI). TG1 produced several plasma proteins and growth factors: albumin, alpha-fetoprotein (AFP), ferritin, carcinoembryonic
antigen, beta-2-microglobulin, polyamine, neuron specific enolase, tissue polypeptide antigen, transferrin (Tf), epidermal
growth factor, and platelet derived growth factor. By analysis of lectin (LcHA)-affinity electrophoresis, to examine the microheterogeneity
of carbohydrate chains of synthetic glycoproteins, TG1 cells cultured with ISRPMI produced only LcHA reactive Tf and AFP based
on core fucose attached to asparagine-linkedN-acetylglucosamine residues instead of LcHA-nonreactive Tf and AFP produced by TG1 cells cultured with fetal bovine serum
(FBS)-containing medium.α1-6 Fucosyltransferase activity was significantly greater in the TG1 cells cultured with ISRPMI (39.9±1.5 pmol · h−1 · mg−1 protein) than cultured with FBS-containing media (18.2±1.2 pmol · h−1 · mg−1 protein). These results have indicated that the selective increase ofα1-6 fucosyltransferase occurred when the cells were cultured with the FBS-free synthetic media. 相似文献
46.
Release of eicosanoids is an important response of macrophages to inflammation and bacterial infection. At low concentrations, bacterial lipopolysaccharide (1-2 micrograms/ml) fails to stimulate eicosanoid release in resident peritoneal macrophages but primes the macrophages for a greatly enhanced release of eicosanoids on stimulation with the calcium ionophore A23187 (0.1 microM) or with phorbol 12-myristate 13-acetate (50 nM), an activator of protein kinase C. Incubation of macrophages with Bordetella pertussis toxin, prior to priming with lipopolysaccharide, inhibited the release of both cyclooxygenase and lipoxygenase products upon A23187 stimulation. Pertussis toxin treatment of macrophages had no effect on eicosanoid release when the stimulus was phorbol 12-myristate 13-acetate. The presence of 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), an effective inhibitor of protein kinase C, during lipopolysaccharide priming and subsequent stimulation significantly inhibited eicosanoid release when phorbol 12-myristate 13-acetate was the stimulus, but did not affect eicosanoid release stimulated by A23187. Based on these results, at least two mechanisms, distinguished by apparent differences in sensitivity to pertussis-toxin-sensitive, guanine-nucleotide-binding proteins and protein kinase C, are involved in eicosanoid secretion by lipopolysaccharide-activated macrophages in response to A23187 and phorbol 12-myristate 13-acetate. 相似文献
47.
J S Allen K Matsunaga T Nakamura F Kitamura T Furukawa S S Hacisalihzade V M Sarich L Stark 《Human biology; an international record of research》1990,62(3):337-352
Smooth-pursuit eye-tracking dysfunction is a putative genetic trait marker for schizophrenia. In this study 88 Japanese schizophrenics from Kyushu and Okinawa were examined for the marker using precise high-resolution instrumentation: 76% of the schizophrenics from Kyushu and 89% of those from Okinawa had pursuit dysfunction. The presence of the culture-neutral smooth-pursuit marker for schizophrenia in Japan demonstrates that the etic concept "schizophrenia" is cross-culturally valid. Furthermore, the ubiquity of the marker in biologically and culturally diverse populations may indicate a limit on the extent of meaningful heterogeneity likely to be discovered within the condition. 相似文献
48.
Ei Matsunaga 《Human genetics》1980,54(1):127-128
Summary Centrometric fission of chromosome 10 is reported in a 25-year-old psychiatric patient and his 51/2-year-old normal daughter. The relevant literature on this subject is briefly reviewed. 相似文献
49.
Naoko Kawamura 《Chromosoma》1979,74(2):179-188
Mosaic silkworms were induced when the hybrid eggs of two strains with different egg color and larval markings were exposed to low temperature. Cytological studies were conducted to find out the relation between mosaic larval pattern and ploidy in reproductive cells along with demonstration of chromosomes in the mosaic embryos. — Mosaic eggs eith the characters of both the father and the hybrid were two types, one with large serosa nuclei (LN-mosaic) and the other with small serosa nuclei (SN-mosaic). The cytological studies demonstrated that LN-mosaic individuals were 2n/4n, while SN-mosaic ones were n/2n. In both types of silkworms, cell ploidy level in nuclei of synkaryon origin was two times that of androgenic ones. — From the results obtained in the present studies as well as in the previous studies, a possible mechanism of induction of mosaicism in silkworms by cold shock is contemplated. 相似文献
50.
An endo-(1→6)-β-D-glucanase (EC 3.2.1), isolated from the culture filtrate of Mucor hiemalis, was purified by ammonium sulphate fractionation and gel filtration. The homogeneity of the enzyme was confirmed by disc electrophoresis. The enzyme had a wide range of temperature and pH stability, high substrate specificity, and an action pattern of the endo-type. 相似文献