全文获取类型
收费全文 | 7856篇 |
免费 | 438篇 |
国内免费 | 3篇 |
出版年
2023年 | 17篇 |
2022年 | 31篇 |
2021年 | 109篇 |
2020年 | 58篇 |
2019年 | 89篇 |
2018年 | 109篇 |
2017年 | 109篇 |
2016年 | 145篇 |
2015年 | 269篇 |
2014年 | 308篇 |
2013年 | 520篇 |
2012年 | 487篇 |
2011年 | 494篇 |
2010年 | 361篇 |
2009年 | 314篇 |
2008年 | 531篇 |
2007年 | 511篇 |
2006年 | 522篇 |
2005年 | 500篇 |
2004年 | 488篇 |
2003年 | 479篇 |
2002年 | 490篇 |
2001年 | 81篇 |
2000年 | 64篇 |
1999年 | 111篇 |
1998年 | 109篇 |
1997年 | 84篇 |
1996年 | 79篇 |
1995年 | 65篇 |
1994年 | 77篇 |
1993年 | 67篇 |
1992年 | 59篇 |
1991年 | 54篇 |
1990年 | 38篇 |
1989年 | 37篇 |
1988年 | 44篇 |
1987年 | 29篇 |
1986年 | 25篇 |
1985年 | 23篇 |
1984年 | 36篇 |
1983年 | 18篇 |
1982年 | 34篇 |
1981年 | 29篇 |
1980年 | 19篇 |
1979年 | 37篇 |
1978年 | 14篇 |
1977年 | 23篇 |
1976年 | 18篇 |
1975年 | 12篇 |
1974年 | 14篇 |
排序方式: 共有8297条查询结果,搜索用时 15 毫秒
21.
Toshiho Nishita Hidetoshi Oshige Hiroharu Matsushita Yutaka Kano Masao Asari 《The Histochemical journal》1989,21(1):8-14
Summary Carbonic anhydrase III has been localized using the avidin-biotin-glucose oxidase complex (ABC) method in the submandibular gland of the rat and hamster. This isozyme, which is predominant in skeletal muscle, was observed in intercalated duct, striated duct and excretory duct cells in the rat submandibular glands. In contrast, only some striated duct cells in hamster submandibular glands were stained. 相似文献
22.
HU-1 mutants of Escherichia coli deficient in DNA binding 总被引:1,自引:0,他引:1
We constructed four mutants of the Escherichia coli hupB gene, encoding HU-1 protein, by synthetic oligodeoxyribonucleotide-directed, site-specific mutagenesis on M13mp18 vectors. The HupBR45 protein contained alterations of Arg58----Gly and Arg61----Gly, and the HupBF3, HupBK2 and HupBA1 proteins contained Phe47----Thr, Lys37----Gln and Ala30----Asp alterations, respectively. HupBF3 and HupBR45 were unable to maintain normal cell growth in a hupA-hupB-himA triple mutant at 42 degrees C, mini-F or RSF1010 proliferation, or Mu phage development in a hupA-hupB double mutant, whereas HupBA1 and HupBK2 supported these cellular activities. DNA-affinity column chromatography showed that the HupBF3 and HupBR45 had reduced affinities to DNA. These observations indicate that two highly conserved Arg residues in the arm structure of the C-terminal half of the HU-1 molecule and a Phe residue in the short beta-sheet connecting the two halves of the molecule are important for the DNA-binding ability and biological functions of this protein. 相似文献
23.
Pheromone clouds sprayed by melon fly males were visually detected by focusing a beam of light at them during dusk when the
males were vibrating their wings. The clouds were sprayed to the front, rear and upper sides of the male. We found that special
morphological structures are used for spraying the pheromone clouds. When a male melon fly engages in calling behavior, sex
pheromone droplets are excreted from his anus. This excretion is wiped off with the tarsus of his hind leg, and then it is
deposited on the sexually dimorphic cubital cell hairs on the wing. During wing vibration, the targal bristles on the 3rd
abdominal segment, which are peculiar to males, are rubbed against the specialized hairs of the cubital cell. Calling males
sprayed clouds of pheromone with these actions.
This paper was presented at the 32nd Annual Meeting of the Japanese Society of Applied Entomology and Zoology (Kochi, April,
1988). 相似文献
24.
Participation of hup gene product in ori2-dependent replication of fertility plasmid F 总被引:3,自引:0,他引:3
The fertility plasmid F'gal was not stably maintained in a hupA-hupB double mutant of Escherichia coli. Moreover, mini-F plasmids pFZY1, pFTC1 and pFTC2 were unable to transform the double mutant, though these plasmids efficiently transformed cells harboring a hupA or hupB single mutation. The composite plasmid pFHS1, which consists of the f5 DNA fragment of F plasmid and the whole DNA of a pSC101 derivative that carries a temperature-sensitive mutation for DNA replication, was not stably maintained in the hup double mutant at 42°C. These findings strongly suggest that HU protein is required for ori2-dependent replication of the F plasmid. 相似文献
25.
Ogawa S Yamakawa H Yamanoi J Nishida S Kano Y Takeshima T Tauchi K Nagashima H 《Theriogenology》1988,29(5):1083-1089
An attempt was made to detect the fluorescent bodies (F-body), using Quinacrine mustard (Q-M) staining in the spermatozoa from eight mammalian species (human, bull, boar, dog, rabbit, rat, mouse, and mastomys) as well as in the cock (used as negative control). Sperm suspension, prepared after rinsing by repeated centrifugation with phosphate buffered saline (PBS), was either stained with Q-M for 24 h or treated with protease and then stained with Q-M for 60 min. The final concentration of Q-M in the mixed staining sperm suspension was 0.025 mg/ml. The examination using a reflecting fluorescent microscope revealed that the F-body found in human sperm was also present in the sperm of all the mammals but not in the cock after 24 h of staining. The enzyme-treated specimens showed higher incidences of F-bodies than specimens stained for 24 h without enzymatic digestion. These findings strongly suggest that the F-body is commonly present in the spermatozoa of many mammalian species. 相似文献
26.
27.
Tadashi Matsunaga Noriyuki Nakamura Naoko Tsuzaki Hiroyuki Takeda 《Applied microbiology and biotechnology》1988,28(4-5):373-376
Summary Among 200 strains of marine bluegreen algae isolated from the coastal areas of Japan, the marine blue-green alga Synechococcus sp. NKBG 040607 excreted glutamate at the highest rate, 82.6% of total amino acids production being glutamate. Synechococcus sp. NKBG 40607 was immobilized in calcium alginate gel. Glutamate production by immobilized cells was double that of native cells. Maximal glutamate production (25 g/cm3 gel per day) of the immobilized cells was observed under a light intensity of 144 Einstein/m2 per second at a cell concentration of 7.5 mg dry cells/cm3 gel. Immobilized cells of Synechococcus sp. can use nitrate as a nitrogen source. Immobilized marine Synechococcus sp. produced 0265 mg/cm3 gel of glutamate for 7 days in the presence of chloramphenicol. 相似文献
28.
Yoshihito Shirai Kenji Hashimoto Hideki Yamaji Hiroyuki Kawahara 《Applied microbiology and biotechnology》1988,29(2-3):113-118
Summary The specific oxygen uptake rate of hybridoma cells immobilized in calcium alginate gel particles was measured, and the observed data was compared with those of non-immobilized cells. The uptake rate of the immobilized cells coincided with that of the non-immobilized hybridoma cells just after immobilization, but increased with cell growth. On the other hand, the cellular glucose consumption rate decreased slightly during the experiments. The increased oxygen uptake rate by immobilized cells was closely related to the formation of cell colonies in the gel particles. 相似文献
29.
Akihiro Hara Hiroyuki Hashimoto Hirofumi Morota Hiroshi Harada Hirofumi Uchimiya 《Journal of plant research》1988,101(2):131-140
Tobacco mesophyll protoplasts were treated with plasmids, pCT2 (17.1 kbp) or pCT2T3 (18.3 kbp), which contained a chimeric aminoglycoside phosphotransferase II (APH(3′)II) gene and an intact nopaline synthase gene. Expression of two marker enzymes, APH(3′)II and nopaline synthase, were analyzed in transformed plants. Four out of 16 transformants obtained by pCT2T3 possessed both enzymes. Upon self-pollination, the progeny of one of transformants (T2) segregated to 153∶4 in terms of resistant and susceptible character to kanamycin, suggesting insertion of foreign genes into three independent chromosomes. The kanamycin resistant character in the rest of transformants showed 3∶1 segregation. DNA blot analysis of the T2 transformant and progenies indicated the presence of two marker genes. 相似文献
30.