全文获取类型
收费全文 | 6721篇 |
免费 | 798篇 |
国内免费 | 1篇 |
专业分类
7520篇 |
出版年
2021年 | 80篇 |
2019年 | 90篇 |
2018年 | 72篇 |
2017年 | 62篇 |
2016年 | 112篇 |
2015年 | 166篇 |
2014年 | 185篇 |
2013年 | 230篇 |
2012年 | 339篇 |
2011年 | 296篇 |
2010年 | 167篇 |
2009年 | 171篇 |
2008年 | 226篇 |
2007年 | 238篇 |
2006年 | 224篇 |
2005年 | 234篇 |
2004年 | 213篇 |
2003年 | 228篇 |
2002年 | 228篇 |
2001年 | 194篇 |
2000年 | 215篇 |
1999年 | 154篇 |
1998年 | 95篇 |
1997年 | 73篇 |
1996年 | 82篇 |
1995年 | 83篇 |
1994年 | 69篇 |
1993年 | 77篇 |
1992年 | 154篇 |
1991年 | 136篇 |
1990年 | 137篇 |
1989年 | 171篇 |
1988年 | 130篇 |
1987年 | 125篇 |
1986年 | 100篇 |
1985年 | 117篇 |
1984年 | 117篇 |
1983年 | 91篇 |
1982年 | 79篇 |
1981年 | 76篇 |
1980年 | 77篇 |
1979年 | 109篇 |
1978年 | 89篇 |
1977年 | 64篇 |
1976年 | 71篇 |
1975年 | 71篇 |
1974年 | 81篇 |
1973年 | 79篇 |
1972年 | 56篇 |
1971年 | 53篇 |
排序方式: 共有7520条查询结果,搜索用时 0 毫秒
71.
Isolation of an evolutionarily conserved epidermal growth factor receptor cDNA from human A431 carcinoma cells 总被引:2,自引:0,他引:2
F A Simmen M L Gope T Z Schulz D A Wright G Carpenter B W O'Malley 《Biochemical and biophysical research communications》1984,124(1):125-132
Complementary DNA corresponding to total poly(A)+-RNA from the human A431 epidermoid carcinoma cell line was cloned in the phage expression vector lambda gt 11. An epidermal growth factor (EGF) receptor cDNA clone was obtained by screening of the expression library with a rabbit polyclonal antibody (IgG), raised to the purified A431 EGF receptor, in combination with [125I]protein A of S. aureus. The cloned cDNA was able to select, by hybridization, messenger RNA which was translated in Xenopus oocytes and yielded an immunoprecipitable EGF receptor protein of Mr = 160,000. The insert of this cDNA (phEGFR-1), is approximately 880 base pairs in length and encodes the carboxyterminal portion of the EGF receptor protein. Its sequence is evolutionarily conserved among vertebrates as shown by hybridization to unique chromosomal DNA sequences from human, baboon, dog, rat, mouse and frog. 相似文献
72.
The 1H-NMR spectrum of cucumber basic blue protein (CBP) has been recorded. Examination of the spectrum of the reduced protein suggests that one or more sidechains exist in conformations which interconvert slowly at ambient temperatures. His 39, His 84 and Met 89 are identified as copper ligands by redox titration and by amino acid sequence homology with plastocyanin and azurin. The importance of a Phe sidechain close to the Met ligand in the potential blue copper site is confirmed. Broadening of His ligand resonances at elevated temperatures reveals an exchange process at the reduced copper centre. 相似文献
73.
The effectiveness of budesonide, a new non-halogenated glucocorticoid administered by nasal inhaler, was evaluated in a double blind comparison with placebo in patients presenting with hay fever. Patients were supplied with antihistamine tablets and eye drops for use when they considered that their symptoms were inadequately controlled by their inhaler. Patients recorded the severity of their symptoms in a daily diary card and visited their general practitioner for assessment weekly for four weeks. All nasal symptoms of hay fever were appreciably reduced in the group taking budesonide and, although their eye symptoms were more severe than in the group taking placebo, they did not use appreciably more eye drops than the latter. The placebo group used appreciably more antihistamine tablets than those in the budesonide group. No patients were withdrawn from the budesonide group because of treatment failure or unacceptable side effects. The results suggest that budesonide is an acceptable and effective treatment for the nasal symptoms of hay fever. 相似文献
74.
75.
76.
77.
An in vitro 51Cr release assay for human antibody-dependent cell-mediated cytotoxicity (ADCC) against HeLa cells infected with respiratory syncytial virus (RSV) has been characterized by using leukophoresed and adherent cell-depleted adult lymphocytes. Lymphoytes from RSV seronegative children were also competent as effector cells. Sera from children with :1) primary and recurrent natural RSV infections, or 2) live attenuated RSV vaccine infection were examined to characterize the behavior of ADCC antibody in vivo. After natural RSV infection ADCC antibody rose and fell more rapidly than neutralizing antibody. In two children undergoing primary RSV infection with attenuated vaccine, neutralizing antibody was formed in the absence of detectable ADCC antibody. The nonparallel behavior of ADCC and neutralizing antibodies suggests the heterogeneity of either the antigen involved or the mechanism of antibody production in the two antibody systems. 相似文献
78.
N Moschonas E de Boer F G Grosveld H H Dahl S Wright C K Shewmaker R A Flavell 《Nucleic acids research》1981,9(17):4391-4401
79.
80.