全文获取类型
收费全文 | 2841篇 |
免费 | 145篇 |
出版年
2021年 | 25篇 |
2020年 | 11篇 |
2019年 | 14篇 |
2018年 | 25篇 |
2017年 | 32篇 |
2016年 | 50篇 |
2015年 | 60篇 |
2014年 | 76篇 |
2013年 | 272篇 |
2012年 | 139篇 |
2011年 | 128篇 |
2010年 | 88篇 |
2009年 | 99篇 |
2008年 | 156篇 |
2007年 | 156篇 |
2006年 | 175篇 |
2005年 | 128篇 |
2004年 | 159篇 |
2003年 | 162篇 |
2002年 | 170篇 |
2001年 | 30篇 |
2000年 | 25篇 |
1999年 | 37篇 |
1998年 | 31篇 |
1997年 | 48篇 |
1996年 | 45篇 |
1995年 | 39篇 |
1994年 | 36篇 |
1993年 | 29篇 |
1992年 | 44篇 |
1991年 | 47篇 |
1990年 | 31篇 |
1989年 | 32篇 |
1988年 | 33篇 |
1987年 | 12篇 |
1986年 | 23篇 |
1985年 | 24篇 |
1984年 | 27篇 |
1983年 | 21篇 |
1982年 | 45篇 |
1981年 | 20篇 |
1980年 | 28篇 |
1979年 | 19篇 |
1978年 | 15篇 |
1977年 | 19篇 |
1976年 | 11篇 |
1974年 | 10篇 |
1973年 | 15篇 |
1969年 | 7篇 |
1966年 | 7篇 |
排序方式: 共有2986条查询结果,搜索用时 15 毫秒
11.
12.
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
13.
Dr. Emiko Matsumoto Kazushige Hirosawa Kiyoshi Takagawa Yoshiki Hotta 《Cell and tissue research》1988,252(2):293-300
Summary A Drosophila visual mutant rdgA has photoreceptive cells which degenerate gradually after eclosion. Fine structure of the retinular cells of rdgA
KS60
and rdgA
K014
was studied during early stages of degeneration to determine the initial morphological defects. The retinular cells of these two alleles showed the following structural abnormality within 1 day after eclosion: (1) rhabdomeres were small and irregular in shape; (2) cisternae of the rough endoplasmic reticulum were more numerous than those in normal retinular cells; (3) submicrovillar cisternae were absent; and (4) lysosomes were fewer than normal. Three-dimensional reconstruction of serial sections of the ommatidia showed that the degeneration of mutant rhabdomeres proceeds more rapidly in regions remote from the nuclei. These results suggest that the process of turnover of rhabdomeric microvilli is abnormal in rdgA. We also confirmed an increase of lysosomes and destruction of cellular organelles, as reported by previous investigators at more advanced stages of degeneration. 相似文献
14.
Summary Biosynthesis and processing of the protective protein for -galactosidase in normal and galactosialidosis fibroblasts were investigated using specific antiserum preparations. A 45-kd precursor was processed to a mature 30-kd protein in normal fibroblasts. The mature protective protein was not detected in any of the twelve galactosialidosis fibroblast strains examined in this study. The precursor was not detected in two cases and in the others was of heterogeneous molecular weight, i.e., normal, abnormally low, or abnormally high. These molecular abnormalities were not correlated with clinical manifestations of the patients. 相似文献
15.
Kiyoshi Morikawa Jun-ichi Hamada Toshiyuki Itaya Makoto Ishikawa Noritoshi Takeichi Masuo Hosokawa Hiroshi Kobayashi 《Cancer immunology, immunotherapy : CII》1988,26(1):18-22
Summary Rat fibrosarcoma cells infected with Friend leukemia virus (FV-KMT-17) grow for a short time and then regress spontaneously in syngeneic hosts. This regression mechanism was examined by analyzing the immunomodulating action of the antitumor drugs busulfan (BU) and cyclophosphamide (CY). In preliminary experiments, the optimum dosages of BU and CY for the enhancement of DTH responses to SRBC were 10 mg/kg and 40 mg/kg respectively. Treatment of rats with BU (10 mg/kg) on day 5 induced the regression of KMT-17 cells, while in contrast, the same drug delayed the spontaneous regression of FV-KMT-17 cells. Pretreatment with CY (40 mg/kg) on day 5 did not affect the growth of KMT-17 or FV-KMT-17 cells. After the same treatment schedule, BU inhibited humoral antibody formation against SRBC and against virus-associated antigen (VAA), NK cell activity, and ADCC effector cell activity. On the other hand, CY did not affect the activities of NK cells or ADCC effector cells, although it significantly augmented the DTH responses to SRBC and the production of antibody to VAA but had no effect on production of antibodies to SRBC. These results suggest that NK cells and ADCC may play an important role in the initial stage of the spontaneous regression of FV-KMT-17 cells.Supported in part by a Grant-in-Aid for Cancer Research from the Japanese Ministry of Education
Abbreviations used: BU, busulfan; CY, cyclophosphamide; PFC assay, plaque forming cell assay; VAA, virus-associated antigen; NK cell, natural killer cell; ADCC, antibody dependent cellular cytotoxicity; MuLV, murine leukemia virus; DTH, delayed type hypersensitivity; SRBC, sheep red blood cells; C.I., cytotoxic index; CRBC, chicken red blood cells; IL-1, interleukin 1; IL-2, interleukin 2; IFN, interferon 相似文献
16.
Esaka Muneharu; Imagi Jun; Suzuki Kanichi; Kubota Kiyoshi 《Plant & cell physiology》1988,29(2):231-235
Ascorbate oxidase activity rapidly increased during callus formationfrom pumpkin fruit tissue. The activity reached a maximum at5 days after transfer and then declined. In callus which hadbeen subcultured at about 4-week intervals for more than oneyear, the activity also increased after transfer to fresh mediumand reached a maximum in the early logarithmic phase of growth.Light had little effect on the appearance of ascorbate oxidaseactivity in pumpkin callus. In the callus grown in the presenceof 10µM CuSO4, the activity was about 10 times that inthe presence of 0.1 µM CuSO4, suggesting that the formatonof ascorbate oxidase in pumpkin callus is stimulated by copper,a prosthetic metal of the enzyme. From 45 to 75% of the totalascorbate oxidase activity in pumpkin cell suspension cultureswas found in the medium. Ascorbate oxidase activity in the medium,as well as that in the cells, increased soon after transferto fresh medium, and reached a maximum at about 5 days. (Received July 2, 1987; Accepted November 21, 1987) 相似文献
17.
18.
Hangil Chang Naohide Yamashita Hiroshi Matsunaga Kiyoshi Kurokawa 《The Journal of membrane biology》1988,103(3):263-271
Summary We have previously reported hyperpolarizing membrane potential changes in a monkey kidney cell line (JTC-12) which has characteristics resembling proximal tubular cells. These hyperpolarizations could be observed spontaneously or evoked by mechanically touching adjacent cells. In this report, we have shown further evidence that these hyperpolarizations are elicited by an increase in membrane conductance to K+ which is caused by an increase in cytosolic Ca2+ concentration. In addition, we have found another type of hyperpolarization which is evoked by applying flow of extracellular fluid to the cell. Intracellular injection of Ca2+ and Sr2+ evoked hyperpolarizations, while intracellular injection of Mn2+ and Ba2+ did not. Intracellular injection of EGTA suppressed both spontaneous and mechanically evoked hyperpolarizations. In Ca2+-free medium, both spontaneous and flow-evoked hyperpolarizations were not observed, while mechanical stimuli consistently evoked hyperpolarization. In Na+-free medium, the incidence of cells showing the spontaneous or flow-evoked hyperpolarization increased, and the amplitude and the duration of the mechanically evoked hyperpolarization became greater. Quinidine inhibited all types of hyperpolarization. These data suggest that hyperpolarizations in JTC-12 cells are due to an increase in Ca2+-activated K+ conductance. 相似文献
19.
Measurement of sulfidopeptide leukotrienes and their metabolism in human synovial fluid of patients with rheumatoid arthritis 总被引:2,自引:0,他引:2
Y Koshihara T Isono H Oda S Karube Y Hayashi 《Prostaglandins, leukotrienes, and essential fatty acids》1988,32(3):113-119
Leukotriene (LT)C4 in the synovial fluid of patients with osteoarthritis deformans (OA) and rheumatoid arthritis (RA) was measured by radioimmunoassay (RIA) after extraction with Sep-Pak C18 cartridge. The amounts of immunoreactive LTC4 (i-LTC4) in samples from patients with OA and RA were not significantly different, being 0.198 +/- 0.018 pmol/ml (n = 11) and 0.179 +/- 0.016 pmol/ml (n = 12), respectively. After separation by high performance liquid chromatography (HPLC) and measurement by RIA, the levels of other sulfidopeptide LTs, such as LTD4 and LTE4, in synovial fluid from patients with RA were found to be significantly higher than those in fluid from patients with OA. The leukocyte number in synovial fluids did not correlate with the i-LTC4 level. The metabolic activities of these synovial fluids were determined by incubating them with 3H-LTC4 and then separating sulfidopeptide LTs by HPLC. The conversion of LTC4 to LTD4 in synovial fluids of patients with OA and RA were similar, but the dipeptidase activity converting LTD4 to LTE4 was higher in fluid from patients with RA. It is suggested that a high level of LTE4 may contribute to exudation of synovial fluid, since LTE4 increases vascular permeability. 相似文献
20.
Kiyoshi Akeo Yasuhiko Tanaka Tatsuji Fujiwara 《In vitro cellular & developmental biology. Plant》1988,24(7):705-710
Summary The endocytotic process in cultured human RPE cells was observed after 1 min, 20 min, and 2 h incubation with cationized ferritin.
Within 1 min the ferritin particles were seen to attach to the cell membrane, especially between microvilli. Uncoated and
coated pits could be recognized on the cell membranes, and uncoated and coated endocytotic vesicles were found in the cytoplasm
after 20 min of incubation. These vesicles were surrounded by abundant microfilaments and had no visible membranes. Loss of
membrane may be an initial step in the process of developing into the irregular clumps of ferritin particles found inside
the plasma membrane. With time, more irregular clumps of ferritin, smaller than the particles introduced during incubation,
appeared just beneath the cell membrane. Lysosomes were adjacent to the clumps of ferritin particles associated with microtobules
and finally degraded these particles. The phagolysosomes containing many particles were surrounded by many microtubules. Small
ferritin particles surrounded but had not entered the rough endoplasmic reticulums, and no particles were seen either around
or in the Golgi apparatus.
Presented at the 7th International Congress of Eye Research, Nagoya, Japan, 27 September 1986. 相似文献