全文获取类型
收费全文 | 6374篇 |
免费 | 284篇 |
国内免费 | 57篇 |
专业分类
耳鼻咽喉 | 93篇 |
儿科学 | 156篇 |
妇产科学 | 52篇 |
基础医学 | 651篇 |
口腔科学 | 120篇 |
临床医学 | 421篇 |
内科学 | 1984篇 |
皮肤病学 | 84篇 |
神经病学 | 503篇 |
特种医学 | 260篇 |
外科学 | 1042篇 |
综合类 | 33篇 |
预防医学 | 130篇 |
眼科学 | 216篇 |
药学 | 313篇 |
中国医学 | 9篇 |
肿瘤学 | 648篇 |
出版年
2023年 | 59篇 |
2022年 | 83篇 |
2021年 | 190篇 |
2020年 | 97篇 |
2019年 | 120篇 |
2018年 | 175篇 |
2017年 | 132篇 |
2016年 | 146篇 |
2015年 | 164篇 |
2014年 | 199篇 |
2013年 | 254篇 |
2012年 | 377篇 |
2011年 | 479篇 |
2010年 | 251篇 |
2009年 | 204篇 |
2008年 | 356篇 |
2007年 | 406篇 |
2006年 | 376篇 |
2005年 | 367篇 |
2004年 | 380篇 |
2003年 | 347篇 |
2002年 | 374篇 |
2001年 | 89篇 |
2000年 | 90篇 |
1999年 | 76篇 |
1998年 | 69篇 |
1997年 | 79篇 |
1996年 | 58篇 |
1995年 | 56篇 |
1994年 | 57篇 |
1993年 | 32篇 |
1992年 | 75篇 |
1991年 | 45篇 |
1990年 | 46篇 |
1989年 | 52篇 |
1988年 | 47篇 |
1987年 | 50篇 |
1986年 | 28篇 |
1985年 | 22篇 |
1984年 | 18篇 |
1983年 | 18篇 |
1982年 | 12篇 |
1979年 | 21篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1973年 | 11篇 |
1972年 | 10篇 |
1970年 | 10篇 |
1969年 | 9篇 |
1967年 | 9篇 |
排序方式: 共有6715条查询结果,搜索用时 0 毫秒
91.
Koichiro Ina Toshio Hayashi Atsushi Araki Seinosuke Kawashima Hirohito Sone Hiroshi Watanabe Takashi Ohrui Koutaro Yokote Minoru Takemoto Kiyoshi Kubota Mitsuhiko Noda Hiroshi Noto Qun‐Fang Ding Jie Zhang Ze‐Yun Yu Byung‐Koo Yoon Hideki Nomura Masafumi Kuzuya Japan CDM Group 《Geriatrics & Gerontology International》2014,14(4):806-810
92.
93.
Nobuaki Sakamoto Huanhuan Hu Akiko Nanri Tetsuya Mizoue Masafumi Eguchi Takeshi Kochi Tohru Nakagawa Toru Honda Shuichiro Yamamoto Takayuki Ogasawara Naoko Sasaki Akiko Nishihara Teppei Imai Toshiaki Miyamoto Makoto Yamamoto Hiroko Okazaki Kentaro Tomita Akihiko Uehara Ai Hori Makiko Shimizu Taizo Murakami Keisuke Kuwahara Ami Fukunaga Isamu Kabe Tomofumi Sone Seitaro Dohi 《Journal of diabetes investigation.》2020,11(3):719-725
94.
Masafumi Harada Risa Ikegami Loku Singgappulige Rosantha Kumara Shinji Kohara Osami Sakata 《RSC advances》2019,9(51):29511
Reverse Monte Carlo (RMC) modeling based on the total structure factor S(Q) obtained from high-energy X-ray diffraction (HEXRD) and the k3χ(k) obtained from extended X-ray absorption fine structure (EXAFS) measurements was employed to determine the 3-dimensional (3D) atomic-scale structure of Pt, Pd, and Rh nanoparticles, with sizes less than 5 nm, synthesized by photoreduction. The total structure factor and Fourier-transformed PDF showed that the first nearest neighbor peak is in accordance with that obtained from conventional EXAFS analysis. RMC constructed 3D models were analyzed in terms of prime structural characteristics such as metal-to-metal bond lengths, first-shell coordination numbers and bond angle distributions. The first-shell coordination numbers and bond angle distributions for the RMC-simulated metal nanoparticles indicated a face-centered cubic (fcc) structure with appropriate number density. Modeling disorder effects in these RMC-simulated metal nanoparticles also revealed substantial differences in bond-length distributions for respective nanoparticles.3-Dimensional atomic-scale structure of metal nanoparticles obtained by RMC-based simulations using HEXRD and EXAFS data. 相似文献
95.
The leucine twenty homeobox (LEUTX) gene,which lacks a histone acetyltransferase domain,is fused to KAT6A in therapy‐related acute myeloid leukemia with t(8;19)(p11;q13) 下载免费PDF全文
96.
Masafumi Yoshinaga Barry P. Rosen 《Proceedings of the National Academy of Sciences of the United States of America》2014,111(21):7701-7706
Arsenic is the most widespread environmental toxin. Substantial amounts of pentavalent organoarsenicals have been used as herbicides, such as monosodium methylarsonic acid (MSMA), and as growth enhancers for animal husbandry, such as roxarsone (4-hydroxy-3-nitrophenylarsonic acid) [Rox(V)]. These undergo environmental degradation to more toxic inorganic arsenite [As(III)]. We previously demonstrated a two-step pathway of degradation of MSMA to As(III) by microbial communities involving sequential reduction to methylarsonous acid [MAs(III)] by one bacterial species and demethylation from MAs(III) to As(III) by another. In this study, the gene responsible for MAs(III) demethylation was identified from an environmental MAs(III)-demethylating isolate, Bacillus sp. MD1. This gene, termed arsenic inducible gene (arsI), is in an arsenic resistance (ars) operon and encodes a nonheme iron-dependent dioxygenase with C⋅As lyase activity. Heterologous expression of ArsI conferred MAs(III)-demethylating activity and MAs(III) resistance to an arsenic-hypersensitive strain of Escherichia coli, demonstrating that MAs(III) demethylation is a detoxification process. Purified ArsI catalyzes Fe2+-dependent MAs(III) demethylation. In addition, ArsI cleaves the C⋅As bond in trivalent roxarsone and other aromatic arsenicals. ArsI homologs are widely distributed in prokaryotes, and we propose that ArsI-catalyzed organoarsenical degradation has a significant impact on the arsenic biogeocycle. To our knowledge, this is the first report of a molecular mechanism for organoarsenic degradation by a C⋅As lyase.The metalloid arsenic is the most common environmental toxic substance, entering the biosphere primarily from geochemical sources, but also through anthropogenic activities (1). Arsenic is a group 1 human carcinogen that ranks first on the Agency for Toxic Substances and Disease Registry Priority List of Hazardous Substances (www.atsdr.cdc.gov/SPL/index.html). Microbial arsenic transformations create a global arsenic biogeocycle (1). These biotransformations include redox cycles between the relatively innocuous pentavalent arsenate and the considerably more toxic and carcinogenic trivalent arsenite (2, 3). In addition, many microbes, both prokaryotic and eukaryotic, have arsM genes for inorganic arsenite [As(III)] S-adenosylmethionine methyltransferases that methylate inorganic As(III) to mono-, di-, and tri-methylated species (4, 5). The genes encoding arsenic transforming enzymes are widely distributed, and these arsenic biotransformations have been proposed to play significant roles in the arsenic biogeocycle and in remodeling the terrain in volcanic areas such as Yellowstone National Park and regions of the world with high amounts of arsenic in soil and water such as West Bengal and Bangladesh (3, 6).Arsenicals, both inorganic and organic, have been used in agriculture in the United States for more than a century (7). Historically, the use of inorganic arsenical pesticides/herbicides has been largely replaced by methylated arsenicals such as monosodium methylarsonic acid (MSMA), which is still in use as an herbicide for turf maintenance on golf courses, sod farms, and highway rights of way, and for weed control on cotton fields (7). More complex pentavalent aromatic arsenicals such as roxarsone [4-hydroxy-3-nitrophenylarsonic acid, Rox(V)] have been largely used since the middle of the 1940s as antimicrobial growth promoters for poultry and swine to control Coccidioides infections and improve weight gain, feed efficiency, and meat pigmentation (8, 9). These aromatic arsenicals are largely excreted unchanged and introduced into the environment when chicken litter is applied to farmland as fertilizer (8). Pentavalent organoarsenicals are relatively benign and less toxic than inorganic arsenicals; however, aromatic (8–10) and methyl (11, 12) arsenicals are degraded into more toxic inorganic forms in the environment, which may contaminate the foods and water supplies. Although microbial degradation of environmental organoarsenicals has been documented (8, 9, 11, 13), no molecular details of the reaction have been reported. We recently demonstrated that a microbial community in Florida golf course soil carries out a two-step pathway of MSMA reduction and demethylation (14). Here we report the isolation of an environmental methylarsonous acid [MAs(III)]-demethylating bacterium Bacillus sp. MD1 (for “MAs(III) demethylating”) from Florida golf course soil and the cloning of the gene, termed arsenic inducible gene (arsI), responsible for MAs(III) demethylation. The gene product, ArsI, is nonheme iron-dependent dioxygenase with C⋅As lyase activity. ArsI cleaves the C⋅As bond in a wide range of trivalent organoarsenicals, including the trivalent roxarsone [Rox(III)], into As(III), which strongly suggests that the environmental pentavalent phenylarsenicals such as Rox(V) also undergo a two-step pathway of sequential reduction and ArsI-catalyzed dearylation, in analogy with the demethylation of MSMA by a microbial community. Thus, ArsI-catalyzed C⋅As bond cleavage is a newly identified mechanism for degradation of organoarsenical herbicides and antimicrobial growth promoters. 相似文献
97.
98.
99.
100.