全文获取类型
收费全文 | 1277篇 |
免费 | 95篇 |
专业分类
1372篇 |
出版年
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 15篇 |
2017年 | 15篇 |
2016年 | 24篇 |
2015年 | 32篇 |
2014年 | 43篇 |
2013年 | 53篇 |
2012年 | 77篇 |
2011年 | 67篇 |
2010年 | 31篇 |
2009年 | 40篇 |
2008年 | 63篇 |
2007年 | 67篇 |
2006年 | 61篇 |
2005年 | 81篇 |
2004年 | 69篇 |
2003年 | 60篇 |
2002年 | 67篇 |
2001年 | 47篇 |
2000年 | 38篇 |
1999年 | 46篇 |
1998年 | 12篇 |
1997年 | 13篇 |
1996年 | 18篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 14篇 |
1992年 | 36篇 |
1991年 | 29篇 |
1990年 | 19篇 |
1989年 | 18篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1986年 | 5篇 |
1985年 | 12篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1974年 | 7篇 |
1973年 | 7篇 |
1972年 | 5篇 |
排序方式: 共有1372条查询结果,搜索用时 15 毫秒
1.
2.
3.
S P Tang T G Spiro K Mukai T Kimura 《Biochemical and biophysical research communications》1973,53(3):869-874
Raman spectra have been recorded for native and selenium substituted adrenodoxin in dilute solution. Adrenodoxin shows three bands at 397, 350 and 297 cm?1, all polarized, which can be associated with the iron-sulfur core. Selenium substitution leaves the 350 cm?1 band essentially unshifted, but the other two bands disappear and are replaced by new bands at 355 and 263 cm?1. The 350 cm?1 band is assigned to stretching of iron-sulfur (cysteine) bonds, while the 397 and 297 cm?1 bands are associated with vibrations of the labile sulfur atoms. The iron-selenium charge transfer bands were observed at 438 and 480 nm for the oxidized form and at 580 nm for the reduced form. The reduced selena-adrenodoxin displayed absorption maxima at 4, 450 and 5, 550 cm?1, which can be assigned to the d-d transitions of high-spin ferrous ion. From this data and the reported g-values of electron paramagnetic resonance signals, the spin-orbit coupling constants were calculated to be 170 and 210 cm?1 for the respective d-d transitions. 相似文献
4.
5.
I Ono I Ishiwata T Nakaguchi M Soma N Tokita C Ishiwata M Mukai S Nozawa H Ishikawa 《Human cell》1989,2(3):272-277
The malignant schwannoma cell line (HKMS) was established from the subcutaneous tumor of Axilla region of a 48-year-old Japanese woman. The HKMS line has the following biological properties. 1. The HKMS cells were spindle in shape and showed neoplastic and pleomorphic features. The monolayer sheet of HKMS cells showed the resemble cell-arrangement with that of the original tumor tissue. 2. The cells showed a stable growth and the serial passages were successively carried out 150 times within 3 years. Their population doubling time is about 40 hours. 3. The chromosome number varied widely, and the modal number was stable at the 78-80. The marker chromosomes were present. 4. The cells were transplanted into the subcutis of nude mice and produced the malignant schwannoma. 相似文献
6.
Summary Transgenic cucumber (Cucumis sativus L.) plants were successfully obtained from hypocotyl explants inoculated with Agrobacterium tumefaciens, which harbored a binary vector plasmid with NOS-nptII, CaMV 35S-I-gus and CaMV 35S-hph genes. Acetosyringone enhanced the efficiency of transformation at the cut surface cells of hypocotyl explants during five days of co-cultivation. Transformed cells were more effectively selected using 20–30 mg/l hygromycin B than using 50–100 mg/l kanamycin. Shoot regeneration occurred within 4–6 wks, and 12 of 21 regenerated plantlets displayed strong GUS expression in the very young leaves. All of 8 GUS-positive R0 plants examined showed single or a few positive bands by Southern blot analysis. The expression of the CaMV 35S-I-gus gene was observed in various tissues and organs of R0 and R1 transgenic cucumber plants. 相似文献
7.
K. ARIHARA, S. OGIHARA, T. MUKAI, M. ITOH AND Y. KONDO. 1996. Fifteen of 353 environmental isolates of lactic acid bacteria consistently showed activity against Listeria monocytogenes, Streptococcus mutans, Actinomyces viscosus , and/or Propionibacterium acnes . Strain T140, isolated from the surface of Japanese pampas grass leaves and identified as Lactobacillus salivarius subsp. salicinius , also had activity against several Lactobacillus species, Staphylococcus aureus and Yersinia enterocolitica . Since the antagonistic factor(s) produced by T140 was sensitive to a proteolytic enzyme, it was concluded that a bacteriocin (named salivacin 140) was involved in the inhibition activity. Strain T140 required a high initial pH (7.5–8.5) in agar plates for bacteriocin production. 相似文献
8.
Susumu Ikegami Yasunori Ooe Takahiko Shimizu Toshihiko Kasahara Tatsuhiko Tsuruta Masako Kijima Minoru Yoshida Teruhiko Beppu 《Development genes and evolution》1993,202(3):144-151
Summary External application of 10 rig/ml (R)-trichostatin A (TSA), a potent and specific inhibitor of mammalian histone deacetylase, to the embryo of the starfish Asterina pectinifera inhibited development during the early gastrula stage before formation of mesenchyme cells. The TSA-sensitive period was limited to the mid-blastula stage before hatching. The pulse-chase experiment clearly demonstrated that TSA induced an accumulation of acetylated histone species in blastulae through inhibition of historic deacetylation. Similar blockage of development at the early gastrula stage was observed with n-butyrate, which has been known as a weak inhibitor of historic deacetylase. These results suggest an intimate role for historic acetylation-deacetylation equilibria in starfish development.
Correspondence to: S. Ikegami 相似文献
9.
Yoshihiro Takasugi Keiji Kawata Takahiko Okuda Yoshihisa Koga Nobuyuki Mizuguchi Shigeaki Yamanaka Shinsuke Watanabe 《Experimental Animals》2003,52(5):429-432
Age-related alterations and differences of weights and those of amino acid concentrations in the cerebrospinal fluid (CSF) were evaluated between Sprague Dawley (SD) rats and Wistar Kyoto (WKY) rats from eight to twenty weeks of age. The weights of SD rats were heavier than WKY rats at all ages. The age-related alterations of the CSF concentration of many amino acids within each strain were significant but showed no significant trend with age. Between the strains, the concentration differences of excitatory and inhibitory amino acids were not frequent although the concentrations of arginine, alanine and threonine were significantly higher in SD rats than in WKY rats. These results suggest that the different CSF concentrations of amino acids may relate to characteristics of rat strains. 相似文献
10.
Tetsuya Tanigawa Yasuo Mizo-oku Kouichi Moriguchi Takashi Suzuki Takahiko Osumi Masaaki Odomi 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,683(2):135
A simple and rapid quantitative method for 13C-labelled urea ([13C]urea) in human serum was developed by using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS). This method is used to establish and normalize the [13C]urea breath test, which is considered as an effective diagnostic method for Helicobacter pylori infection. HPLC-APCI-MS, involving a simple pretreatment process such as diluting serum with water, was shown to be able to discriminate the extrinsic [13C]urea from intrinsic urea present at high concentration in serum. In addition, a 13C nuclear magnetic resonance spectroscopic quantitative method for [13C]urea in human urine is also described. The precision and accuracy of measured concentrations in these two methods were found to be within the acceptable limit. An application of these methods to investigate the pharmacokinetic profile of orally administered [13C]urea in human serum and urine is also presented. 相似文献