全文获取类型
收费全文 | 5346篇 |
免费 | 345篇 |
国内免费 | 4篇 |
专业分类
5695篇 |
出版年
2022年 | 32篇 |
2021年 | 41篇 |
2020年 | 22篇 |
2019年 | 36篇 |
2018年 | 57篇 |
2017年 | 49篇 |
2016年 | 74篇 |
2015年 | 123篇 |
2014年 | 142篇 |
2013年 | 272篇 |
2012年 | 255篇 |
2011年 | 253篇 |
2010年 | 158篇 |
2009年 | 162篇 |
2008年 | 249篇 |
2007年 | 264篇 |
2006年 | 235篇 |
2005年 | 265篇 |
2004年 | 225篇 |
2003年 | 273篇 |
2002年 | 233篇 |
2001年 | 200篇 |
2000年 | 217篇 |
1999年 | 174篇 |
1998年 | 72篇 |
1997年 | 62篇 |
1996年 | 53篇 |
1995年 | 57篇 |
1994年 | 51篇 |
1993年 | 51篇 |
1992年 | 120篇 |
1991年 | 116篇 |
1990年 | 106篇 |
1989年 | 109篇 |
1988年 | 100篇 |
1987年 | 74篇 |
1986年 | 77篇 |
1985年 | 51篇 |
1984年 | 66篇 |
1983年 | 52篇 |
1982年 | 43篇 |
1981年 | 39篇 |
1980年 | 22篇 |
1979年 | 43篇 |
1978年 | 34篇 |
1977年 | 31篇 |
1976年 | 27篇 |
1974年 | 33篇 |
1971年 | 27篇 |
1970年 | 29篇 |
排序方式: 共有5695条查询结果,搜索用时 15 毫秒
1.
2.
T Tobe S Minoshima S Yamase N H Choi M Tomita N Shimizu 《Cytogenetics and cell genetics》1991,57(4):193-195
SP-40,40 is a serum glycoprotein consisting of two different subunits (alpha and beta) assembled into a dimer by disulfide bonds. Northern blot hybridization, using total RNA from several cell lines, showed that SP-40,40 is expressed in glioblastoma and testicular tumor cells, as well as hepatoma cells. Spot blot hybridization of flow-sorted human chromosomes, using a SP-40,40 cDNA fragment as a probe, localized the gene for SP-40,40 to human chromosome 8. This gene has been given the designation CLI, for complement lysis inhibitor, by the Human Gene Nomenclature Committee. 相似文献
3.
An examination of four species of Cirsium disclosed the presence of two new flavonoids in C. lineare. The structure of one was 5,4′-dihydroxy-6,7,3′-trimethoxyflavone (cirsilineol) 4′-monoglucoside and the other 5,3′,4′-trihydroxy-6,7-dimethoxyflavone (cirsiliol) 4′-monoglucoside. Luteolin 7-glucoside was found in C. suffultum, and pectolinarin and linarin in C. kamtschaticum and C. pectinellum. 相似文献
4.
T Maoka A Arai M Shimizu T Matsuno 《Comparative biochemistry and physiology. B, Comparative biochemistry》1986,83(1):121-124
Racemic mixtures of (3RS, 3'RS)-zeaxanthin were separated into the three optical isomers, (3R, 3'R)-zeaxanthin (1), (3R,3'S;meso)-zeaxanthin (2) and (3S,3'S)-zeaxanthin (3), by converting to their corresponding dibenzoates and by using HPLC on an optical resolution column Sumipax OA-2000. According to this procedure, it has been shown that only (1) is isolated from higher plants, shellfish, starfish, sea squirt, sea cucumber and then examined; on the other hand (1), (2) and (3) are isolated from zeaxanthin fraction of shrimp, fish and turtle examined. This is the first isolation of enantiomeric and meso-zeaxanthin in nature. 相似文献
5.
Akira Shimizu 《Journal of Ethology》1992,10(2):85-102
Anoplius eous Yasumatsu (Hymenoptera, Pompilidae) exhibits some outstanding nesting behavior. Females excavate a unicellular or multicellular
nest in wet ground, or dig a single-celled nest in rotten wood, or build clustered mud cells in narrow spaces between walls
of such substances as wood or vinyl sheets. The latter nest-type has been unknown within the subfamily Pompilinae. Females
prepare a nest-cell before hunting, and construct it further after hunting, leaving the prey near the nest (behavior-formula:
IVPTIOC). They transport their prey backward on the ground, grasping it in their mandibles by any part of the legs, and forward
on the surface film of water or on the ground, grasping it by the middle part of the 1st or 2nd legs. Their only prey is the
adult female semi-aquatic spider,Pardosa pseudoannulata (Lycosidae). These nesting and provisioning behavior patterns are compared with those of other pompilids. The position of
the present species in the behavioral evolution of the Pompilidae is suggested. 相似文献
6.
T Nimura M Okada M Shimizu M Kawabe T Itoh M Iwasaki H Kimura T Takeuchi 《The Annals of physiological anthropology》1990,9(4):329-333
Motorcyclists who work in some offices sometimes complained of coldness, pain and numbness of upper limbs. We studied how to discriminate between vibration syndrome and local fatigue of the motorcyclists. Subjects are 42 motorcyclists of an office in Aichi prefecture. 25 of them held several letters in their left hand when they delivered the letters. They complained of coldness, pain and numbness in the left upper limbs more than in the right limbs (p less than 0.01). We think that it is the local fatigue rather than the disorder of vibration syndrome that causes such symptoms. So it is very important to recognize the existence of local fatigue in order to know how to discriminate between vibration syndrome and local fatigue of the motorcyclists. 相似文献
7.
Masanori Shinzato Mikihiro Shamoto Satoru Hosokawa Chiyuki Kaneko Akido Osada Miyuki Shimizu Asako Yoshida 《Biotechnic & histochemistry》1995,70(3):114-118
The present study shows that Langerhans cells can be differentiated from Interdigitating cells at the light microscopic level. Superficial lymph nodes and skin taken from necropsies and the lymph nodes of dermatopathic lymphadenopathy (DPL) were used for this experiment. Sections of lymph node and skin were embedded using the acetone, methyl benzoate and xylene (AMeX) method and dendritic cells were immunostained with anti S-100 protein antibody (S-100, and OKT-6 (CD1a) using the restaining method. Langerhans cells in the skin were positive for both CD1a and S-100. Dendritic cells positive for both CD1a and S-100, and dendritic cells positive for S-100, but not for CD1a were observed in superficial lymph nodes. In normal superficial lymph nodes, there were more interdigitating cells than Langerhans cells. The majority of the dendritic cells in the DPL were Langerhans cells. We conclude that the S-100 and CD1a positive cells are Langerhans cells, and the S-100 positive-CD1a negative cells are interdigitating cells. 相似文献
8.
9.
The syntheses of two new radioactive probes derived from cardiolipin and phosphatidylcholine are reported. These probes are derivatives of natural lipids and contain an amine-specific benzaldehyde in the head-group region. This functional group allows a choice of timing of the reaction (e.g., after equilibration and detergent removal) because an irreversible covalent bond is formed only upon the addition of reducing agent. These probes, as well as a benzaldehyde analogue of phosphatidic acid, and a water-soluble benzaldehyde reagent were covalently attached to bovine heart cytochrome c oxidase. After reconstitution into vesicles, the lipid-benzaldehyde probes selectively incorporated into the smaller polypeptides of the enzyme, while the remaining subunits (I-IV) exhibited little incorporation of label. The accessibility of amine groups labeled under the conditions used here was independent of the structural and charge differences between the benzaldehyde probes. This suggests that all three lipid probes react with polypeptides of the cytochrome c oxidase complex at general contact sites for membrane phospholipids. A water-soluble benzaldehyde reagent predominantly labeled subunits IV, Va, and Vb and polypeptides of VII-VIII. A comparison of these results facilitates a more refined view of the disposition of polypeptides of cytochrome c oxidase in respect to the lipid and aqueous phases. 相似文献
10.
Changes in electrophoretic mobility histograms of splenocytes and thymocytes were studied in plasmacytoma X5563-bearing mice as an indicator of response to treatment with mitomycin C (MMC) alone or combined with the immunomodulator Krestin (PSK). Tumor growth was inhibited by 80-90% in the MMC-treated and was further inhibited in the MMC and PSK-treated group. Electrophoretic mobility histograms of splenocytes were used to determine the fraction of cells having intermediate mobility between high mobility (T cells) and low mobility (B cells). This fraction of intermediate-mobility cells increased in tumor-bearing mice, but a normal electrophoretic mobility pattern was obtained following successful antitumor treatment. In the electrophoretic mobility histogram of thymocytes, on the other hand, the low-mobility cells (cortical thymocytes) decreased in number during tumor growth and were further reduced in the MMC-treated group. This reduction was less in the MMC and PSK-treated group. These results suggest that combined therapy with MMC and PSK prevents damage of the host defence mechanism and allows more efficient antitumor treatment. Analysis of electrophoretic mobility histograms of splenocytes and thymocytes using a fully automated cell electrophoretic instrument makes possible the rapid evaluation of the immunological effects of drug therapy of tumor-bearing mice. 相似文献