全文获取类型
收费全文 | 3262篇 |
免费 | 198篇 |
国内免费 | 2篇 |
出版年
2022年 | 11篇 |
2021年 | 21篇 |
2020年 | 12篇 |
2019年 | 30篇 |
2018年 | 47篇 |
2017年 | 28篇 |
2016年 | 50篇 |
2015年 | 78篇 |
2014年 | 90篇 |
2013年 | 203篇 |
2012年 | 183篇 |
2011年 | 192篇 |
2010年 | 99篇 |
2009年 | 116篇 |
2008年 | 177篇 |
2007年 | 216篇 |
2006年 | 197篇 |
2005年 | 187篇 |
2004年 | 184篇 |
2003年 | 185篇 |
2002年 | 188篇 |
2001年 | 93篇 |
2000年 | 73篇 |
1999年 | 84篇 |
1998年 | 62篇 |
1997年 | 43篇 |
1996年 | 37篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1993年 | 24篇 |
1992年 | 47篇 |
1991年 | 25篇 |
1990年 | 38篇 |
1989年 | 39篇 |
1988年 | 31篇 |
1987年 | 22篇 |
1986年 | 26篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 28篇 |
1980年 | 22篇 |
1979年 | 16篇 |
1977年 | 12篇 |
1974年 | 11篇 |
1973年 | 14篇 |
1972年 | 13篇 |
1969年 | 10篇 |
1968年 | 12篇 |
排序方式: 共有3462条查询结果,搜索用时 15 毫秒
61.
Enzymic analyses of aqueous extracts of barley obtained at 25–100° demonstrated an exponential relationship between β-d-glucan content and temperature. Purified β-d-glucans, in particular those from extracts made at 40° and 100°, were compared by the Smith-degradation method followed by g.l.c. analysis of the methyl and the trimethylsilyl ethers of the products. All extracts yielded qualitatively the same products, including oligosaccharides which were characteristic of sequences of adjacent (1→3)-linkages. The material extracted at 100° contained relatively more of these sequences, and also showed a much higher specific viscosity, than did the material extracted at low temperatures. The structural implications of these findings are discussed. 相似文献
62.
I Ihara H Ueda A Suzuki M Kawakami 《Biochemical and biophysical research communications》1982,107(4):1185-1190
63.
Kohei Kawashima Eiji Watanabe Ken-ichi Isobe Michinori Ogura Ei-ichi Nagura Kazumasa Yamada Itsuro Sobue Kenji Mizoguchi Yasuhiko Ito Yoshiyuki Nagai Izumi Nakashima 《Cellular immunology》1982,67(2):279-286
During the course of immunization of (C3H × DBA/2)F1 mice (genotype H-2k/b) with L cell (H-2k/k)/L1210 leukemia cell (H-2d/d) hybrids and L1210 leukemia cells, some of them produced a good titer of anti-self-H-2 (H-2d) antibodies. Antigens recognized by this anti-self-H-2 antiserum were shown to be controlled by the H-2K-IA-IB-IJ-IE subregions of the H-2d but not H-2k nor H-2b haplotypes of parental as well as F1 origins and to have a tissue distribution identical to that of class 1 H-2 (H-2K/D) antigens. 相似文献
64.
K Kawai A Fukamizu Y Kawakami M Matsumura K Mitsui K Murakami K Yamashita 《Endocrinologia japonica》1991,38(6):603-609
A 54-year-old woman was referred to our hospital for the treatment of a tumor of the right chest wall. Clinical examination revealed hypertension, hypokalemia, metabolic alkalosis, hyperaldosteronism and hyperreninemia. Computed tomography and an abdominal echogram indicated a tumor in the right phrenic area and two tumors in the retroperitoneum near the pancreas head. After the surgical resection of these tumors, the primary reninism was diminished. The pathological diagnosis of these tumors was leiomyosarcoma. Plasma active and inactive (trypsin-activated) renin activities (PRA) were 85.7 and 38.9 ng angiotensin I/ml/h, respectively. These PRA did not respond to either postural stimulation or suppression by the volume expansion. Active and inactive renin activities in a right phrenic area tumor were 208 and 32 ng angiotensin I/mg protein /h, respectively. Those of an abdominal tumor were 196 and 30 ng angiotensin I/mg protein/h, respectively. Renin mRNA identical in molecular size to that of the human kidney was identified by northern blot analysis. This is the first case report of renin producing leiomyosarcoma derived from the lung, which is characterized by relatively lower plasma prorenin concentrations. 相似文献
65.
Yoshiyuki Suzuki 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1991,569(1-2)
The electrophoretic approaches for detection of mutant proteins in inherited diseases are briefly reviewed and discussed. Mutation of a protein, known to be associated with a specific inherited disease, is detected by immunoblotting, immunoprecipitation or enzyme staining, combined with various electrophoretic techniques. Some instrumental and technological devices for two-dimensional electrophoresis have been reported for the screening of mutant proteins in diseases of currently unknown etiology. 相似文献
66.
Ty Element-Induced Temperature-Sensitive Mutations of Saccharomyces Cerevisiae 总被引:5,自引:0,他引:5
下载免费PDF全文
![点击此处可从《Genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Temperature-sensitive mutants of Saccharomyces cerevisiae were isolated by insertional mutagenesis using the HIS3 marked retrotransposon TyH3HIS3. In such mutants, the TyHIS3 insertions are expected to identify loci which encode genes essential for cell growth at high temperatures but dispensable at low temperatures. Five mutations were isolated and named hit for high temperature growth. The hit1-1 mutation was located on chromosome X and conferred the pet phenotype. Two hit2 mutations, hit2-1 and hit2-2, were located on chromosome III and caused the deletion of the PET18 locus which has been shown to encode a gene required for growth at high temperatures. The hit3-1 mutation was located on chromosome VI and affected the CDC26 gene. The hit4-1 mutation was located on chromosome XIII. These hit mutations were analyzed in an attempt to identify novel genes involved in the heat shock response. The hit1-1 mutation caused a defect in synthesis of a 74-kD heat shock protein. Western blot analysis revealed that the heat shock protein corresponded to the SSC1 protein, a member of the yeast hsp70 family. In the hit1-1 mutant, the TyHIS3 insertion caused a deletion of a 3-kb DNA segment between the delta 1 and delta 4 sequences near the SUP4 locus. The 1031-bp wild-type HIT1 DNA which contained an open reading frame encoding a protein of 164 amino acids and the AGG arginine tRNA gene complemented all hit1-1 mutant phenotypes, indicating that the mutant phenotypes were caused by the deletion of these genes. The pleiotropy of the HIT1 locus was analyzed by constructing a disruption mutation of each gene in vitro and transplacing it to the chromosome. This analysis revealed that the HIT1 gene essential for growth at high temperatures encodes the 164-amino acid protein. The arginine tRNA gene, named HSX1, is essential for growth on a nonfermentable carbon source at high temperatures and for synthesis of the SSC1 heat shock protein. 相似文献
67.
We have identified a positive regulatory cis-acting element of the adhesion molecule on glia (AMOG)/Na,K-ATPase beta 2 subunit gene as GAGGCGGGG at position -87 to -79 by transient transfection assay using B103 cells (rat neuroblastoma cell line). The newly identified AMOG regulatory element (AMRE) enhanced the promoter activity in a mutually compensating manner with the Sp1 element at position -147 to -142. AMRE acts as a positive regulatory element not only in B103 cells but also in 3Y1 (rat embryo cell line) cells to roughly the same extent and in MDCK (canine kidney cell line) cells to a lesser extent. AMRE also enhances other gene promoters, such as myelin basic protein (MBP) and herpes simplex virus (HSV) thymidine kinase (TK) gene promoters. The element is not a typical enhancer element because when it is introduced downstream of the HSV TK promoter, it has no enhancing activity. 相似文献
68.
Brush border myosin I heavy chain (MIHC), known previously as the brush border 110-kDa protein, contains an amino-terminal sequence which is highly homologous to the globular head domain of conventional myosin II heavy chain (MIIHC). The carboxyl-terminal sequence of MIHC completely diverges from that of MIIHC and functions as calmodulin-binding and membrane-interaction sites. In this investigation, we determined the structural organization of the bovine MIHC by isolating a set of genomic segments containing the whole MIHC gene. The bovine MIHC gene is 26 kilobase pairs long and consists of 28 exons. At the homologous amino-terminal portion of MIHC, many introns are located at positions equivalent to those of the rat MIIHC gene and the amoeba MIHC gene. At the carboxyl-terminal sequence of MIHC, the putative calmodulin-binding and membrane-interacting domains are specified by discrete sets of exons. These findings support the view that the amino-terminal head portions of MIHC and MIIHC evolved from a common ancestral origin and also that the MIHC protein was generated as a result of fusion of discrete genomic segments encoding different functional and structural protein domains. Analysis of tissue expression of the MIHC mRNA was also extended in this investigation, and the results indicated that this mRNA is expressed in some tissues other than the intestines. 相似文献
69.
Sachio Hayashi Masaharu Nonoguchi Yoshihiko Shimokawa Mikihiko Tubouchi Yoshiyuki Takasaki Kiyohisa Imada 《Journal of industrial microbiology & biotechnology》1992,9(2):145-147
Summary Two extracellular -fructofuranosidases (E-1 andE-2) fromAureobasidium sp. ATCC 20524, producing 1-kestose (1F--fructofuranosyl-sucrose) from sucrose, were purified to homogeneity. Molecular weights of the enzymes were estimated to be about 304000 (E-1) and 315000 (E-2) Da by gel filtration. The enzymes contained 33% (w/w) (E-1) and 27% (w/w) (E-2) carbohydrate. TheK
m values for sucrose ofE-1 andE-2 andE-2 were 0.34 and 0.28 M, respectively. were 0.34 and 0.28 M, respectively. The enzymatic profiles of these enzymes were almost identical to intracellular enzymesP-1 andP-2 except for the differences in carbohydrate content andK
m values ofE-2 andP-2. 相似文献
70.
A Yoshimura C Fujitsuka K Kawakami N Ozawa H Ojala N Fujitsuka 《Journal of applied physiology》1992,73(5):1925-1931
With the use of myosin adenosinetriphosphatase (ATPase) and immunofluorescence staining methods, the adaptive responses of intrafusal and extrafusal fibers to endurance swimming were studied in frozen sections of rat soleus (SOL) and extensor digitorum longus (EDL) muscles. Glycogen depletion confirmed muscle fatigue at the end of a standardized bout of exercise. No significant age-dependent changes in myosin isoforms were detected in any fibers. The 12-wk training increased type I fibers by 10.9% in the SOL and type IIa fibers in the EDL by 16.6%. In trained muscle sections, both staining methods identified a permuted chain fiber, expressed the same as the myosin isoform in the bag2 fiber. However, no exercise-induced change of myosin isoform profile was found in the bag1 and bag2 fibers. Myosin ATPase (and immunofluorescence) staining showed the percentage of permuted chain fibers increased from 0 to 6.7% (5.6%) after 6 wk of training and to 19.2% (14.1%) after 12 wk of training and that it was still at 6.1% (4.2%) 10 wks after training. A novel myosin isoform may thus be expressed in nuclear chain fibers by repetitive recruitment of muscle spindles. 相似文献