全文获取类型
收费全文 | 4300篇 |
免费 | 194篇 |
国内免费 | 1篇 |
专业分类
4495篇 |
出版年
2022年 | 14篇 |
2021年 | 27篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 33篇 |
2017年 | 36篇 |
2016年 | 60篇 |
2015年 | 93篇 |
2014年 | 110篇 |
2013年 | 478篇 |
2012年 | 214篇 |
2011年 | 225篇 |
2010年 | 155篇 |
2009年 | 147篇 |
2008年 | 221篇 |
2007年 | 259篇 |
2006年 | 233篇 |
2005年 | 262篇 |
2004年 | 296篇 |
2003年 | 234篇 |
2002年 | 246篇 |
2001年 | 34篇 |
2000年 | 34篇 |
1999年 | 45篇 |
1998年 | 54篇 |
1997年 | 54篇 |
1996年 | 34篇 |
1995年 | 44篇 |
1994年 | 45篇 |
1993年 | 54篇 |
1992年 | 52篇 |
1991年 | 34篇 |
1990年 | 28篇 |
1989年 | 36篇 |
1988年 | 40篇 |
1987年 | 36篇 |
1986年 | 38篇 |
1985年 | 40篇 |
1984年 | 42篇 |
1983年 | 38篇 |
1982年 | 48篇 |
1981年 | 48篇 |
1980年 | 40篇 |
1979年 | 25篇 |
1978年 | 25篇 |
1977年 | 22篇 |
1976年 | 28篇 |
1975年 | 18篇 |
1974年 | 19篇 |
1973年 | 18篇 |
排序方式: 共有4495条查询结果,搜索用时 15 毫秒
91.
Yukio Hirayama Mamiko Yoshimura Yuriko Ozeki Isamu Sugawara Tadashi Udagawa Satoru Mizuno Naoki Itano Koji Kimata Aki Tamaru Hisashi Ogura Kazuo Kobayashi Sohkichi Matsumoto 《PLoS pathogens》2009,5(10)
In spite of the importance of hyaluronan in host protection against infectious organisms in the alveolar spaces, its role in mycobacterial infection is unknown. In a previous study, we found that mycobacteria interact with hyaluronan on lung epithelial cells. Here, we have analyzed the role of hyaluronan after mycobacterial infection was established and found that pathogenic mycobacteria can grow by utilizing hyaluronan as a carbon source. Both mouse and human possess 3 kinds of hyaluronan synthases (HAS), designated HAS1, HAS2, and HAS3. Utilizing individual HAS-transfected cells, we show that HAS1 and HAS3 but not HAS2 support growth of mycobacteria. We found that the major hyaluronan synthase expressed in the lung is HAS1, and that its expression was increased after infection with Mycobacterium tuberculosis. Histochemical analysis demonstrated that hyaluronan profoundly accumulated in the granulomatous legion of the lungs in M. tuberculosis-infected mice and rhesus monkeys that died from tuberculosis. We detected hyaluronidase activity in the lysate of mycobacteria and showed that it was critical for hyaluronan-dependent extracellular growth. Finally, we showed that L-Ascorbic acid 6-hexadecanoate, a hyaluronidase inhibitor, suppressed growth of mycobacteria in vivo. Taken together, our data show that pathogenic mycobacteria exploit an intrinsic host-protective molecule, hyaluronan, to grow in the respiratory tract and demonstrate the potential usefulness of hyaluronidase inhibitors against mycobacterial diseases. 相似文献
92.
Takahiro Sakai Ikuo Miura Satomi Yamada-Ishibashi Yayoi Wakita Yuki Kohara Yukiko Yamazaki Takeshi Inoue Ryo Kominami Kazuo Moriwaki Toshihiko Shiroishi Hiromichi Yonekawa Yoshiaki Kikkawa 《Experimental Animals》2004,53(2):151-154
We updated a database of microsatellite marker polymorphisms found in inbred strains of the mouse, most of which were derived from the wild stocks of four Mus musculus subspecies, M. m. domesticus, M. m. musculus, M. m.castaneus and M. m. molossinus. The major aim of constructing this database was to establish the genetic status of these inbred strains as resources for linkage analysis and positional cloning. The inbred strains incorporated in our database are A/J, C57BL/6J, CBA/J, DBA/2J, SM/J, SWR/J, 129Sv/J, MSM/Ms, JF1/Ms, CAST/Ei, NC/Nga, BLG2/Ms, NJL/Ms, PGN2/Ms, SK/CamEi and SWN/Ms, which have not or have only been poorly incorporated in the Whitehead Institute/MIT (WI/MIT) microsatellite database. The number of polymorphic microsatellite loci incorporated in our database is over 1,000 in all strains, and the URL site for our database is located at http:// www.shigen.nig.ac.jp /mouse/mmdbj/mouse.html. 相似文献
93.
Measurement of Serine Acetyltransferase Activity in Crude Plant Extracts by a Coupled Assay System Using Cysteine Synthase 总被引:3,自引:0,他引:3
Nakamura Katsuhito; Hayama Atsushi; Masada Masahiro; Fukushima Kazuo; Tamura Goro 《Plant & cell physiology》1987,28(5):885-891
Serine acetyltransferase (SATase) (EC 2.3.1.30
[EC]
) catalyzes theformation of Oacetyl-L-serine (OAS) from L-serine in the presenceof acetyl-CoA. A novel assay method was developed for measuringthis enzyme activity in extracts from plant tissues. The assayconsists of a coupled system in which the OAS formed is convertedto cysteine by the addition of cysteine synthase (CSase) (EC4.2.99.8
[EC]
). Cysteine thus formed is determined colorimetricallyand serves as a measure for SATase activity. This method israpid, simple and sensitive, and can be readily adapted formeasurement of SATase activity in crude tissue extracts or homogenates. (Received January 14, 1987; Accepted April 27, 1987) 相似文献
94.
95.
Temporal and spatial changes in gene expression,metabolite accumulation and phytohormone content in rice seedlings grown under drought stress conditions 下载免费PDF全文
Daisuke Todaka Yu Zhao Takuya Yoshida Madoka Kudo Satoshi Kidokoro Junya Mizoi Ken‐Suke Kodaira Yumiko Takebayashi Mikiko Kojima Hitoshi Sakakibara Kiminori Toyooka Mayuko Sato Alisdair R. Fernie Kazuo Shinozaki Kazuko Yamaguchi‐Shinozaki 《The Plant journal : for cell and molecular biology》2017,90(1):61-78
96.
Li Y Kawamura Y Fujiwara N Naka T Liu H Huang X Kobayashi K Ezaki T 《Systematic and applied microbiology》2003,26(4):523-528
Classification of strain W3-B1, which was isolated from condensation water in the Russian space laboratory Mir, was investigated by a polyphasic taxonomic approach. Cells of strain W3-B1 were nonmotile, asporogenous, gram-negative slender rods with rounded ends. 16S rRNA gene sequence analysis indicated that organism should be placed in the genus Chryseobacterium. This organism contains menaquinone MK-6 as the predominent isoprenoid quinone and 3-OH iso 17:0 (40%), iso 15:0 (33%) as the major fatty acids. Phylogenetically, the nearest relative of strain W3-B1 is Chryseobacterium meningosepticum with sequence similarity of 98.4%, but DNA-DNA hybridization resulted in similarity values of only 52.3%. The G+C mol% is 34.6 mol%. Based upon results obtained by morphological, biochemical, chemotaxonomic, and molecular methods, strain W3-B1 was clearly distinguishable from other Chryseobacterium species. For these reasons, a novel species of family Flavobacteriaceae is proposed; strain W3-B1(T) (= GTC 862(T) = JCM 11413(T) = DSM 14571(T)) is the type strain. 相似文献
97.
Karyotypes and serum transferrin patterns were examined in Asian and Oceanian black rats (R. rattus). Japanese R. r. tanezumi and Malayan R. r. diardii had 2n=42, but Australian and New Guinea R. r. rattus showed 2n=38 chromosomes. F1 hybrids between Japanese and Australian rats and Malayan and New Guinea rats had 2n=40 chromosomes which consists of the two genomes of both parents. Although various matings between the F1 hybrids were made, only one F2 male rat with 2n=39 chromosomes was obtained. The F1 hybrids seem to be semisterile. Parental transferrin phenotypes were TfR in Japanese rats and TfCD in Oceanian rats. F1 hybrids examined showed TfRD in both male and female and one F2 hybrid had TfR type transferrin. Based on the above investigations, it is suggested that Asian and Oceanian black rats are geographically isolated and evolved different chromosomal and serum transferrin characteristics, but the sexual isolation of the two groups is incomplete at the present time.Contribution No. 826 from the National Institute of Genetics, Japan. Supported by a grant-in-aid from the Ministry of Education of Japan (Scientific Expedition in 1968, No. 8801 in 1969 and No. 9001 in 1970). 相似文献
98.
Chikara Komiya Kyoichiro Tsuchiya Kumiko Shiba Yasutaka Miyachi Shunsaku Furuke Noriko Shimazu Shinobu Yamaguchi Kazuo Kanno Yoshihiro Ogawa 《PloS one》2016,11(3)
Type 2 diabetes mellitus (T2DM) is associated with a high incidence of non-alcoholic fatty liver disease (NAFLD) related to obesity and insulin resistance. Currently, medical interventions for NAFLD have focused on diet control and exercise to reduce body weight, and there is a requirement for effective pharmacological therapies. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are oral antidiabetic drugs that promote the urinary excretion of glucose by blocking its reabsorption in renal proximal tubules. SGLT2 inhibitors lower blood glucose independent of insulin action and are expected to reduce body weight because of urinary calorie loss. Here we show that an SGLT2 inhibitor ipragliflozin improves hepatic steatosis in high-fat diet-induced and leptin-deficient (ob/ob) obese mice irrespective of body weight reduction. In the obese mice, ipragliflozin-induced hyperphagia occurred to increase energy intake, attenuating body weight reduction with increased epididymal fat mass. There is an inverse correlation between weights of liver and epididymal fat in ipragliflozin-treated obese mice, suggesting that ipragliflozin treatment promotes normotopic fat accumulation in the epididymal fat and prevents ectopic fat accumulation in the liver. Despite increased adiposity, ipragliflozin ameliorates obesity-associated inflammation and insulin resistance in epididymal fat. Clinically, ipragliflozin improves liver dysfunction in patients with T2DM irrespective of body weight reduction. These findings provide new insight into the effects of SGLT2 inhibitors on energy homeostasis and fat accumulation and indicate their potential therapeutic efficacy in T2DM-associated hepatic steatosis. 相似文献
99.
100.