全文获取类型
收费全文 | 3118篇 |
免费 | 204篇 |
国内免费 | 2篇 |
专业分类
3324篇 |
出版年
2022年 | 14篇 |
2021年 | 28篇 |
2020年 | 17篇 |
2019年 | 33篇 |
2018年 | 32篇 |
2017年 | 34篇 |
2016年 | 49篇 |
2015年 | 76篇 |
2014年 | 85篇 |
2013年 | 208篇 |
2012年 | 129篇 |
2011年 | 163篇 |
2010年 | 94篇 |
2009年 | 86篇 |
2008年 | 135篇 |
2007年 | 149篇 |
2006年 | 166篇 |
2005年 | 151篇 |
2004年 | 167篇 |
2003年 | 160篇 |
2002年 | 126篇 |
2001年 | 112篇 |
2000年 | 121篇 |
1999年 | 80篇 |
1998年 | 61篇 |
1997年 | 48篇 |
1996年 | 36篇 |
1995年 | 29篇 |
1994年 | 34篇 |
1993年 | 44篇 |
1992年 | 64篇 |
1991年 | 45篇 |
1990年 | 49篇 |
1989年 | 34篇 |
1988年 | 38篇 |
1987年 | 30篇 |
1986年 | 27篇 |
1985年 | 36篇 |
1984年 | 26篇 |
1983年 | 23篇 |
1982年 | 29篇 |
1981年 | 24篇 |
1980年 | 18篇 |
1979年 | 26篇 |
1978年 | 24篇 |
1977年 | 29篇 |
1976年 | 14篇 |
1974年 | 16篇 |
1971年 | 14篇 |
1970年 | 15篇 |
排序方式: 共有3324条查询结果,搜索用时 15 毫秒
21.
22.
23.
Sakano S Hasegawa Y Murata Y Ito T Genda E Iwata H Ishiguro N Seo H 《Biochemical and biophysical research communications》2002,293(2):680-685
Basic fibroblast growth factor (bFGF) is reported to stimulate repair of fracture and bony defects in in vivo animal studies. However, most studies performed in vitro demonstrate inhibitory effect of bFGF on cartilage and bone differentiation. To understand the discrepancy observed in in vivo and in vitro studies, we evaluated the effect of bFGF on chondro-osteogenesis initiated by bone matrix powder (MP). MP was implanted in the murine hamstring muscles with or without administration of bFGF. Injection of 1 microg of bFGF markedly reduced the size of heterotopic bone induced by MP, as detected by X-ray. Injection of 10 microg of bFGF completely inhibited ossification and only fibrous tissues were observed at the site of MP implantation. The expressions of alkaline phosphatase and osteocalcin mRNAs, markers for bone differentiation, were completely suppressed by 10 microg of bFGF. These results demonstrate the inhibitory effect of bFGF on endochondral ossification in vivo, implicating a precaution for its use in musculo-skeletal disorders. 相似文献
24.
Akira C. Saito Toshihiko Ogura Kei Fujiwara Satoshi Murata Shin-ichiro M. Nomura 《PloS one》2014,9(9)
Here, we report a method for introducing large objects of up to a micrometer in diameter into cultured mammalian cells by electrofusion of giant unilamellar vesicles. We prepared GUVs containing various artificial objects using a water-in-oil (w/o) emulsion centrifugation method. GUVs and dispersed HeLa cells were exposed to an alternating current (AC) field to induce a linear cell–GUV alignment, and then a direct current (DC) pulse was applied to facilitate transient electrofusion. With uniformly sized fluorescent beads as size indexes, we successfully and efficiently introduced beads of 1 µm in diameter into living cells along with a plasmid mammalian expression vector. Our electrofusion did not affect cell viability. After the electrofusion, cells proliferated normally until confluence was reached, and the introduced fluorescent beads were inherited during cell division. Analysis by both confocal microscopy and flow cytometry supported these findings. As an alternative approach, we also introduced a designed nanostructure (DNA origami) into live cells. The results we report here represent a milestone for designing artificial symbiosis of functionally active objects (such as micro-machines) in living cells. Moreover, our technique can be used for drug delivery, tissue engineering, and cell manipulation. 相似文献
25.
Toba T Murata K Futamura J Nakanishi K Takahashi B Takemoto N Tomino M Nakatsuka T Imajo S Goto M Yamamura T Miyake S Annoura H 《Bioorganic & medicinal chemistry》2012,20(9):2850-2859
A series of truncated analogs of α-galactosylceramide with altered ceramide moiety was prepared, and evaluated for Th2-biased response in the context of IL-4/IFN-γ ratio. Phytosphingosine-modified analogs including cyclic, aromatic and ethereal compounds as well as the C-glycoside analog of OCH (2) with their cytokine inducing profile are disclosed. 相似文献
26.
Organization of microtubules (MTs) in relation to the behavior of nuclei was examined in dividing binucleate cells ofAdiantum capillus-veneris L. To induce binucleate cells, caffeine, an inhibitor of formation of the cell plate, was applied at 4 mM to synchronously
dividing protonemal cells during cytokinesis (Murata and Wada 1993). Formation of the preprophase band (PPB) during the next
cell cycle was examined in non-centrifuged and centrifuged cells. The two nuclei were separated or associated with one another
in both non-centrifuged and centrifuged cells, although the location of the nuclei in the cylindrical protonemal cells was
different (Murata and Wada 1993). Irrespective of centrifugation, a single PPB was formed around the nuclei in cells with
associated nuclei. Two PPBs were formed in cells with separated nuclei in centrifuged cells. Patterns of mitosis and cytokinesis
varied, depending on the location of the PPB and the distribution of the nuclei. The role of the nucleus in formation of the
PPB is discussed. 相似文献
27.
FIA functions as an early signal component of abscisic acid signal cascade in Vicia faba guard cells
Sugiyama Y Uraji M Watanabe-Sugimoto M Okuma E Munemasa S Shimoishi Y Nakamura Y Mori IC Iwai S Murata Y 《Journal of experimental botany》2012,63(3):1357-1365
An abscisic acid (ABA)-insensitive Vicia faba mutant, fia (fava bean impaired in ABA-induced stomatal closure) had previously been isolated. In this study, it was investigated how FIA functions in ABA signalling in guard cells of Vicia faba. Unlike ABA, methyl jasmonate (MeJA), H(2)O(2), and nitric oxide (NO) induced stomatal closure in the fia mutant. ABA did not induce production of either reactive oxygen species or NO in the mutant. Moreover, ABA did not suppress inward-rectifying K(+) (K(in)) currents or activate ABA-activated protein kinase (AAPK) in mutant guard cells. These results suggest that FIA functions as an early signal component upstream of AAPK activation in ABA signalling but does not function in MeJA signalling in guard cells of Vicia faba. 相似文献
28.
Murata S Mochizuki K Nakazawa T Kondo T Nakamura N Yamashita H Urata Y Ashihara T Katoh R 《Cytometry》2002,49(3):91-95
BACKGROUND: Aspiration biopsy cytology of thyroid tumors has been used more frequently in recent times to differentiate between malignant and benign lesions. Chromatin patterns of the tumor cell nuclei are one of most important factors for cytologic diagnosis. The interpretation of nuclear chromatin patterns is subjective and more difficult than that of nuclear size or shape. In the present report, we investigated how to detect underlying chromatin characteristics of benign and malignant thyroid tumor cells by means of texture and factor analyses. METHODS: We employed a computer-aided system in which light microscopy was combined with an image processor and monochrome camera. Using this system, 100 randomly selected cells in a Papanicolaou stained, aspiration biopsy cytologic smear in each case of 39 benign and malignant thyroid tumor cases were digitized. We applied two-dimensional and higher texture analyses with the use of co-occurrence and run-length matrices to analyze the chromatin patterns. Factor analysis was used to determine whether a large number of independent variables actually measured one or more underlying common variables. RESULTS: According to parameters with high factor-loading values, the morphologic chromatin characters were classified into three categories according to heterogeneity, contrast, and homogeneity of chromatin patterns. On the basis of analyses with these morphologic categories, nuclei of papillary carcinoma showed higher contrast of chromatin patterns than did those of the benign group. Moreover, there was a variety of contrasting chromatin patterns among cells in each papillary carcinoma case in comparison with the benign group. In contrast, follicular carcinomas showed a significant difference in the standard deviation of factor 3, which indicated more monotonous chromatin patterns among cells in each follicular carcinoma case than in each benign case. CONCLUSION: We believe that this technique, using texture and factor analyses, is useful in the detection of underlying characteristics of nuclear chromatin patterns in aspiration biopsy cytology. 相似文献
29.
Hiroo Horinishi Shuichi Hashizume Masaharu Seguchi Kazuko Takahashi 《Biochemical and biophysical research communications》1975,67(3):1136-1143
A soluble fraction from Escherichia coli B was found to incorporate methionine into 95°C CCl3COOH-insoluble fraction. The incorporation required methionyl-tRNA synthetase, methionine tRNA, ATP, Mg2+ and bovine milk casein. The casein could be replaced by arginylated bovine serum albumin and arginylated bovine α-lactalbumin. A mixture of 19 amino acids other than methionine and GTP had no effect on the incorporation. KCl was rather inhibitory. Puromycin, RNase A and trypsin inhibited the incorporation, while DNase I did not. The soluble fraction also incorporated the methionyl moiety of methionyl-tRNA. This incorporation was not affected by the addition of free methionine. 相似文献
30.
Summary Processes in the development of intestinal metaplasia of the stomach were investigated from the morphological and histochemical approaches using light and electron microscopic techniques. The specimens taken from 38 gastric carcinomas and 15 gastric and/or duodenal ulcers were subjected to this study. Morphological appearances of the intestinal metaplasia observed in routine examination with hematoxylin and eosin staining was able to be divided into complete and incomplete metaplasia by the light and electron microscopic histochemical stainings of the mucosubstances. The columnar cells at the area of the incomplete metaplasia had both the properties of the intestinal epithelia and the gastric foveolar epithelia. The incomplete as well as the complete metaplasia arose from the generative cells at the isthmus of the gland. The generative cells, however, sometimes gradually transformed to produce the complete metaplastic cells. The two processes of the development of the intestinal metaplasia were proposed and discussed. 相似文献